Preheat the oven to 180°C/ 350°F/ Gas Mark 4. Grease and line a 23cm springform cake time with greaseproof paper.
Cream the butter and sugar with an electric whisk for 2 minutes or until light and fluffy.
Add the eggs one at a time, mixing well between additions. Then add the almond extract and whisk for 2 minutes until fully incorporated.
Lace the ground almonds, polenta and baking powder in a separate bowl and mix well.
Lightly fold the dry mixture into the butter, sugar and egg mixture until just smooth.
Gently fold the raspberries into the butter.
Spoon the butter into the prepared tin, smooth over the surface and scatter over the flaked almonds.
Bake the cake for 45 minutes or until golden brown and a skewer inserted comes out with only a few crumbs.
Leave the cake in the tin to cool slightly.
Then transfer to a wire rack to cool completely before serving.
Store in the fridge in an airtight container for up to three days.