Preheat your oven to 350°F (175°C) and line a standard cupcake pan with liners.

In a large mixing bowl, sift together the all-purpose flour, Dutch cocoa powder, baking powder, baking soda, salt, and optional espresso powder. Set aside.

Cream the softened butter and sugar in another bowl until light and fluffy, about 3-4 minutes.

Add the egg, egg yolk, and vanilla extract to the creamed mixture, mixing until smooth. Then blend in the milk and sour cream until velvety.

Carefully add the dry ingredients to the wet mixture in three additions, mixing slowly until just combined.

Fill cupcake liners about three-quarters full with the batter, then bake for 17-20 minutes or until a toothpick comes out clean.

Let the cupcakes cool in the pan for about 10 minutes before transferring them to a wire rack to cool completely.

For the ganache, heat heavy cream until simmering, then pour over chopped chocolate and let sit before stirring until smooth. Mix in raspberry preserves.

Beat the softened butter for the buttercream until fluffy, then gradually add the powdered sugar and ground raspberries until light and creamy.

Once cooled, use a cupcake corer to remove some center from each cupcake and pipe the ganache into the hollow.

Frost with raspberry buttercream and garnish with fresh raspberries for elegant presentation.