175g or 6 ounces of butter
175g or 6 ounces of light brown muscovado sugar
3 eggs, separated
The grated rind and juice of half a lemon
125g or 4½ ounces of self-raising flour
2.5ml or ½ teaspoon baking powder
75g or 3 ounces chopped walnuts
40g or 1 ¼ ounce of ground almonds
15ml or tablespoon of milk
200g or 7 ounces of carrots, peeled and grated
2.5ml or a half teaspoon of grated nutmeg
For the icing:

150g or 5 ounces of mascarpone cheese
25g or 1 ounce of icing sugar, sifted
15ml or 1 tablespoon of lemon juice
30ml or two tablespoons of chopped walnuts,to decorate

Grease and line an 18cm or 7 inches deep round, fixed base, cake tin.

Place the butter and sugar in a bowl and beat together until creamy.

Beat in the egg yolks and then stir in the lemon rind.

Stir in the flour, baking powder, walnuts, almonds and milk.

Mix the grated carrots and lemon juice together and fold in.

Whisk the egg whites until stiff and fold into the carrot cake mixture.

Transfer to the prepared tin. Cover with pleated, greased, parchment paper and tie with string to secure.

Add 750ml or 1 and a quarter pints of hot water to the pressure cooker.

Place the cake tin in the steamer basket and place in the pressure cooker. If the cake tin will not fit in your steamer basket, place a shallow heatproof upturned saucer or small plate in the base of your pressure cooker before adding the water, and place the cake tin on top.

Place the lid on the pressure cooker but do not align the handles to lock and seal.

Bring to the boil and steam only, without pressure, for 15 minutes.

Fit the lid and lock by aligning the handles. Turn the pressure limiting valve to 1 and bring to pressure and cook for 30 minutes.

Reduce the steam naturally, then remove the pressure limiting valve. Press down the safety button to unlock the handles and open the lid.

Carefully remove the tin from the cooker. Place on a wire rack and remove the parchment paper. Leave to stand for 10 minutes, then turn out on to a wire rack to cool.

Mix the mascarpone cheese, icing sugar and lemon juice together and spread over the top of the cake.

Sprinkle with walnuts and serve.