This cake takes a little time to make, but the results are really worth it. A rich and buttery cake is made from ground pecans and crushed digestives, baked, then filled and topped with a caramel icing.
Preheat oven to 180 C / Gas 4. Grease and line two 23cm round cake tins with baking parchment.
Combine the biscuit crumbs, 65g ground pecans, flour, baking powder and salt.
In a large bowl, cream the butter and the light dark brown soft sugar until fluffy. Slowly beat in the egg yolks, one at a time. Stir in the vanilla. Alternately add the milk and the crumb mixture while beating on low.
Beat the egg whites in a bowl until foamy. Add 4 tablespoons sugar slowly and beat to soft peaks. Fold into the crumb batter and pour into the tins.
Bake for 25 minutes or until a skewer comes out clean. Cool in the tins on a rack about 10 minutes, then invert and cool completely.
To make the icing, heat 2 tablespoon sugar in a saucepan over medium heat until it turns golden. Remove from heat and add 60g of the butter; swirl. Whisk in the dark brown soft sugar and place back on the heat. Bring to the boil, stirring constantly. Add the cream and bring back to the boil. Boil for 1 minute and remove caramel from heat.
Place icing sugar in a large bowl and mixing on medium speed, slowly drizzle in the caramel. Beat until the bottom of the bowl is just barely warm, about 5 minutes. Add the remaining butter, 15g at a time. Beat until smooth and chill icing until ready to ice the cake. Ice the cake and press the pecans into the sides.