Marble cake with vanilla and chocolate

Ingredients

• 300 g wheat flour
• 225 g butter
• 200 g powdered sugar
• 4 large eggs
• 1 heaped teaspoon baking powder
• 120 ml milk
• 120 g dark chocolate
• 1 tablespoon teaspoon vanilla extract
• 1 teaspoon of rum oil
• a pinch of salt
• 45 g milk chocolate
• 45 g dark chocolate
• 2 tablespoons butter