Bake Off Bake Along: Week 5: Sugar-Free Spiced Sweet Potato Loaf

This week's challenges are most certainly that. Despite the number of 'healthy' baking books that are around, its not as simple as just picking one recipe and running with it. Not unless you're pretty healthy anyway and your cupboards are stocked up with everything that Whole Foods or Planet Organic stock.

Sugar is my kryptonite. Even when I'm being healthier, I eat tonnes of sugar laden fruit so was keen this week to make something entirely sugar-free.

Of course Gwyneth Paltrow comes up trumps with sugar-free recipes. I spotted this recipe for sweet potato muffins and mixed things up a little to make a loaf cake with what I already had in my cupboards. This mix is enough to make a dozen muffins or a 1lb loaf.

So if you fancy giving it a go, here's a few tips on substituting ingredients:

• Liquid sweeteners are a great substitute for sugar, just be careful of the ratios as volumes and weights always differ. This guide is a great help to give you an idea. In Gwynnie's recipe, rice malt syrup is used as its a complex sugar that slowly absorbs into the bloodstream. I don't have this and I've never seen it in my local supermarket so opted to use maple syrup instead.
• Stevia is also a good alternative. As a natural sweetener its preferable to other sweeteners you'll find in the baking aisle like aspartame. Although, as stevia is twice as sweet as sugar, you only need to use half the quantity.
• As sugar is hygroscopic, it adds moisture to baking. It also gives a different structure and taste when it caramelises which is why different sugars are suited to different recipes. You may want a short crumb in biscuits and pastry, but something moist and golden in brownies and cakes. This is also the case with sweeteners. Coconut sugar, honey or maple syrup are great alternatives for any type of brown sugar where you need a caramel taste. 
• As a general rule of thumb, natural sweeteners bake quicker than regular sugars, especially honey. If you're adapting a recipe, check on your bake 5-10 minutes before listed in the recipe.
• Another popular alternative is agave due to its low GI qualities, although as with honey, it is high in fructose so be careful with using too much. 

Mostly its a taste preference, we see cake and expect it to be sweet. Sweet potatoes are naturally sweet so in this recipe you can get away with only adding 2 tablespoons of maple syrup!

See how I got on with the previous week's challenges:

   

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Recipe: Spiced Sweet Potato Cake with Marshmallow Frosting

I'll make pretty much anything to use up what's lurking around in the cupboard or fridge. I hate to waste food. Usually this involves some form of dinner which, in my family, is known as an 'around the world dinner'. By this, you can expect any combination of leftovers of all sorts of cuisines.

I couldn't quite face eating a bag full of sweet potatoes to myself this week so set out to find a suitable use for them. After making a few pumpkin cakes with cans of Libby's last year I was keen to try sweet potato and see how they compare.

This sweet potato cake is slightly more dense than the pumpkin ones I made last year and has much more flavour. But, if you do have a can of Libby's pumpkin purée hanging around, you can substitute with the same quantity.

Spiced sweet potato cake with marshmallow frosting
(Recipe slightly adapted from Smitten Kitchen)

680g sweet potatoes (approximately 2-3)
115g unsalted butter, room temperature
190g soft light brown sugar
2 large eggs
1/2 tsp vanilla extract
250g plain flour
1 3/4 tsp baking powder
1/2 bicarbonate of soda
1/2 tsp salt
1 tsp ground cinnamon
1/4 tsp ground ginger
1/4 tsp ground cloves, or mixed spice

Marshmallow frosting:

3 large egg whites
180g golden caster sugar
pinch pf salt
1/4 tsp cream of tartar
1/2 tsp vanilla extract

Prick the sweet potatoes all over and roast in the oven at 180 degrees for 30 - 45 minutes. They may need a turning a few times. Once cooked they'll be soft and look a little deflated. Leave to cool completely. If you're baking in advance, leave them in the fridge for up to 3 days, otherwise give them plenty of time to cool before moving onto the cake.

Heat the oven to 170 degrees and grease and line an 8 - 9 inch round springform tin, or an 8 - 9 inch square tin.

Peel the sweet potatoes and mash until smooth (don't be tempted to blitz in the blender, your mix will be too loose).

Cream together the butter and sugar until light and fluffy. Gradually add the eggs in one at a time, mixing well after each addition. Add the vanilla extract.

Gently fold in the sweet potato, followed by all the dry ingredients. Continue until well incorporated. Pour the batter into the prepared cake tin, smooth the top with a knife and bake for 35 - 40 minutes. Once baked, a skewer inserted into the middle should come out clean. Leave to cool for 10 minutes in the tin before turning out to cool completely on a wire cooling rack.

To make the frosting, add the egg whites, sugar, salt and cream of tartar to a heatproof bowl and place over a pan of barely simmering water. Whisk for approximately 3 minutes, until the sugar has fully dissolved. Remove the bowl from the saucepan and continue to whisk with an electric mixer for a further 4 - 7 minutes on a high speed, until stiff, glossy peaks form. Add the vanilla and mix to combine.

To decorate, spread a thin layer of the marshmallow onto the cake with a palette knife or spatula. Then, with a piping bag or sandwich bag, pipe small dollops over the thin frosting layer. With a kitchen torch, lightly brown the marshmallow dollops until browned.

Find my recipe for sweet potato brownies here if you'd like to try them another way.

Alternatively, you could substitute the same quantity of pumpkin for sweet potato in my spiced pumpkin mini cakes or in my pumpkin praline cake.

Homemade Burger & Sweet Potato Chips

Time for a change this week - a savoury recipe. This is my ultimate burger recipe, a combination of all my favourite burger things but also a good foundation to start with and add your own favourite fillings.

You don't need any fancy tools, but the recipes include a few tricks I've learnt to help.

In case you were wondering, my ultimate burger starts with a toasted brioche bun, topped with one quarter pounder, burger sauce, grilled halloumi, cos lettuce, plum tomatoes and caramelised onion relish. Served with herby baked sweet potato chips and washed down with a Nutella milkshake.

Without further ado,

Brioche burger buns
(Recipe adapted from Rachel Khoo, makes 6 for burgers or 12 for sliders)

My personal favourite burger bun is brioche, below is the recipe I use. Regular shop bought buns of your choice are perfectly good also. Spread a little butter over the cut sides and grill before serving.

260g strong plain white flour
25g caster sugar
5g salt
2tsp dried instant milk
70ml warm milk
3 medium eggs
100g softened butter (cubed)

Egg wash:
1 egg, beaten
2tbsp milk
2tsp sesame seeds

Mix together the flour, sugar and salt with a dough hook in a mixer on a low speed. Continue to mix whilst slowly adding the yeast, milk and eggs until incorporated, approximately 2 minutes. Turn up to a medium speed and continue to mix for a further 5 minutes.

Once soft and elastic, tip into a greased bowl, cover with cling film and leave to prove in a warm place for 1 hour.

Dust your work surface and hands with flour, roll the proved dough into a long rectangle. Slice into 6 (or 12 for sliders), shape each individual bun and place on a large lined tray. Brush with the egg wash.

Heat the oven to 180 degrees. Brush once more and sprinkle the sesame seeds on top. Bake for 20 minutes until golden. Cool on a wire rack before using for your burgers.

Hamburger patties
(Recipe adapted from hamburger gourmet)

 In order to make the most tender, juicy patties, handle them as little as possible. Keep a bowl of warm water to hand when shaping the patties, dip your fingers in after each one to stop them sticking. A burger press can help to make uniformly sized patties, but using your hands is just as good. After shaping, press a thumbprint into the centre to allow for even cooking when they expand with the heat. Season with salt which will form a nice crust whilst cooking and stack them up between waxed discs or greaseproof paper. Don't be tempted to make your patties too thick, they'll only take longer to cook through and loose their tenderness. To make a quarter pounder, you will need 150-170g of minced beef (you should be able to get around 3 patties out of a regular 500g supermarket pack).

Always cook on a high heat in order to get a patty that's crusty on the outside and tender in the middle. Cook the thumbprint side down first to allow an expansion in the heat. Flip over with a spatula and press down, once only, in a short, sharp motion. For blue, cook for 2 minutes on each side; rare, 3 minutes; medium, 4 minutes and well done, 5 minutes.

Fillings

Feel free to use a combination of your favourite cheeses, sauces and relishes. Bear in mind, some cheeses melt better than others and most have completely different flavours when pairing with relishes.

Sweet potato chips

1 medium - large sweet potato per person
To season, dried herbs of your choice, salt and 1tbsp of oil per serving

Heat the oven to 180 degrees. Peel the sweet potatoes and cut into long 1cm chips. Place into a resealable sandwich bag. Add the seasoning, seal and shake the bag to give the chips a good even coat.

Spread the chips evenly onto a baking tray and bake for 30 - 40 minutes until golden and slightly crispy on the edges.

Nutella milkshake
(Makes 2, double up as required)

500ml milk
2 scoops vanilla ice cream
2-3tbsps Nutella

Place all ingredients in a blender and blitz until well combined and smooth.

Pour into glasses to serve.

Serving

In order to have everything ready at the same time, assembled burgers can be kept warm in the oven for a short while on a low heat, around 160 degrees.