Pre-heat the oven to 180 degrees, gas 4. Grease three 15cm (6 in) sandwich tins then line the base of each tin with baking parchment.
Measure the butter, sugar, eggs, flour, baking powder and salted caramel extract into a large bowl and beat until thoroughly blended. Divide the mixture evenly between the tins and level out.
Bake in the pre-heated oven for about 20 minutes or until well risen and the tops of the sponge springs back when lightly pressed with a finger. Leave to cool in the tins for a few minutes then turn out, peel off the parchment and finish cooling on a wire rack.