Gluten-free brown-butter sweet potato loaf cake with mascarpone frosting

Season
Autumn/Winter
Skill level
Keen cook
Preparation Time
1 hour, plus cooling
Cooking Time
1 hour and 20 minutes
Serves
Serves 8
Categories
Vegetarian
Categories
Indulgent

Brown-butter, warming spices and creamy, tangy mascarpone icing make this unassuming sweet potato loaf cake into something really special. Enjoy with a big cup of coffee.

As always with baking, make sure all your cake ingredients are at room temperature when you start.

Ingredients

  • 1 large, sweet potato (300g)
  • 200g unsalted butter
  • 200g soft light brown sugar
  • 4 medium free-range eggs
  • 65ml milk
  • 1 teaspoon vanilla extract
  • Zest of ½ an orange
  • 240g gluten free plain flour
  • 60g ground almonds
  • ½ teaspoon xanthan gum
  • 1 1/4 teaspoons baking powder
  • 1 teaspoon baking soda
  • ½ teaspoon fine salt
  • 1 tablespoon ground cinnamon
  • 1 teaspoon ground ginger
  • ½ teaspoon ground nutmeg
  • ¼ teaspoon ground all spice

For the mascarpone icing:

  • 50g salted butter, softened
  • 200g icing sugar
  • 250g full-fat mascarpone cheese
  • 1 tablespoon orange juice
  • ½ teaspoon vanilla extract

Method

  1. 1Preheat the oven to 220ºC / 200ºC fan / Gas mark 7. Prick the sweet potato all over with a fork, place on a tray and bake in the oven for 40-45 minutes, or until tender. Let cool, then cut in half and scoop out the flesh. Place in a bowl to one side.
  2. 2Reduce the oven temp to 180ºC / 160ºC fan / Gas mark 4 and grease and line a 2lb loaf tin.
  3. 3Put the butter in a small saucepan and place over a low heat. Melt the butter gently, swirling the pan every so often, until the butter turns golden brown. You’ll know it’s almost ready when the splattering and sizzling dies down and it smells overwhelmingly nutty and delicious.
  4. 4Pour into a small bowl, scraping out all the little brown bits (that’s where all the flavour is) and allow to cool a little.
  5. 5Add the sugar to a large mixing bowl and pour over the butter. Whisk until pale and fluffy. Add the sweet potato puree and whisk until well combined. Add in the eggs, one by one, whisking well between each addition. Whisk in the milk, vanilla extract and orange zest.
  6. 6In a large bowl, sift together the plain flour, ground almonds, xanthan gum, baking powder, baking soda, salt, cinnamon, ginger, nutmeg and all spice. Add the wet ingredients and stir to combine.
  7. 7Pour the cake batter into your prepared loaf tin and smooth out the top. Place in the oven and bake for 1 hour 20 minutes, or until risen, golden and a skewer inserted comes out clean/with just a few stray crumbs attached. If the loaf starts browning too quickly, cover the top with some foil.
  8. 8Rest the cake in the tin for 10 minutes, then remove and place on a wire rack to cool.
  9. 9To make the mascarpone icing, place the butter in a mixing bowl and, using an electric whisk, beat until fluffy. Sift the icing sugar in in two stages, beating until smooth. Add the mascarpone, followed by the orange zest and vanilla extract and whisk together once more until thick, smooth and creamy.
  10. 10Spread the icing over the top of the loaf cake, finishing with a few decorative swooshes on top.