Preheat the oven to 175°C.
Mix flour, baking powder, icing sugar, and almond flour together.
Stir in melted butter until the mixture is smooth.
Whip egg whites to soft peaks, gradually adding granulated sugar until firm peaks form. Fold one-third of the egg whites into the batter to loosen it, then gently fold in the remaining whites.
Pour the batter into a greased and floured mold. Press raspberries into the batter.
Optionally, seal a baking ring with foil, extending it above the sides, and place on a perforated baking sheet.
Sprinkle with sliced almonds and extra raspberry pieces.
Bake for about 30-35 minutes until lightly golden, and a knife inserted comes out clean.
Let cool completely for best flavor, especially if refrigerated overnight.