Preheat oven to 180 degrees C. Grease and flour a 22cm springform pan.
Blueberries: In a medium bowl combine blueberries, sugar, 2 tablespoons flour and 2 tablespoons grated lemon zest. Toss to coat berries then pour into the prepared pan.
Cake: In a large bowl cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time then stir in the almond essence and grated lemon zest.
Stir together flour and the baking powder. Beat into butter mixture alternately with the milk; mixing just until incorporated. Pour batter over the berries in the pan.
Bake in the preheated oven for 60 to 70 minutes or until a toothpick inserted into the centre of the cake comes out clean.
Place serving plate over the top of the pan and carefully invert cake and plate together so that the berries end up on top. Carefully unlock the buckle on the side of the pan and remove. Sprinkle toasted almonds on top of cake and serve warm.