Beat the butter and sugar with an electric whisk until creamy, then add the eggs one at a time, followed by the clotted cream. Fold in the flour, almond or vanilla extract and baking powder, and mix until just combined. Dollop spoonfuls (it will be quite a thick batter) into the tin over the peaches and smooth over the surface. Bake for 50 mins-1 hr or until a skewer comes out clean when inserted into the middle. Leave to cool in the tin, then flip onto a plate when at room temperature. Serve the cake with ice cream or more clotted cream, sprinkled with the toasted flaked almonds. It will keep for two days in an airtight container in a cool place but is best eaten within a day.