Preheat oven to 180°C (356°F). Grease a 26 cm springform pan with butter and dust with flour. Place on a baking sheet.
Whip 3 eggs, 150 grams sugar, and 0.5 bottle rum aroma for about 5 minutes until creamy.
Mix 180 g flour, 1 tablespoon cocoa powder, and 0.5 pack baking powder. Sift over the egg mixture and fold in along with 80 g melted butter until well combined.
Pour batter into prepared pan, smooth the top, and bake in the lower half of the oven for 20 minutes until a skewer inserted in the center comes out clean.
Let the cake cool in the pan for about 10 minutes, then turn out and cool completely.
Spread the cooled cake with strawberry jam, if desired.
Mix sour cream, powdered sugar, and lemon juice. Prepare gelatine according to package instructions and stir into the mixture.
Whip cream until stiff peaks form and fold into the gelatine mixture.
Spread the cream over the cake, smooth the top, and refrigerate for 2 hours until set.
Remove the cake from the springform pan and halve it. Place the two halves side by side on a serving plate.
Slice the strawberries except for 4 whole ones. Arrange the sliced strawberries on top and place the 4 whole strawberries in the center as the body.
Prepare the icing with water according to package instructions and brush the strawberries with it.
Refrigerate the butterfly cake until ready to serve. Optional: insert mikado sticks as feelers.