Preheat the oven to 160°C (325°F) Gas mark 3. Melt the butter in a small pan or in the microwave and leave to cool. Lightly butter a 20cm loose-bottomed cake tin.
Put the flour, baking powder, sugar, eggs, almond extract and melted butter into a bowl. Using a hand-held mixer, beat until smooth. Spread half into the prepared tin.
Peel and core the apples and then thickly slice. Add them in layer on top of the sponge mixture, piling them into the centre. Using two tablespoons, spoon the rest of the sponge mixture on top to cover the apples completely.
Scatter over the almonds and bake for 1 ¼ hours until golden and a skewer comes out clean in the middle. Leave for 5 minutes, then dust with the icing sugar. Remove from the tin and cut into slices. Serve warm on plates with the ice cream.