Combine cocoa and chopped bittersweet chocolate in a small bowl.

Whisk in boiling water until chocolate is melted and the mixture is blended smoothly.

In a large bowl, cream softened butter and sugar together until light and fluffy.

Add eggs, one at a time, beating well after each addition until fully incorporated.

In a separate bowl, combine flour, baking powder, and salt.

Gradually add the dry ingredients to the creamed mixture alternately with the red wine and chocolate mixture, beating well after each addition.

Fill paper-lined muffin cups three-fourths full with batter.

Bake in a preheated oven at 350°F (175°C) for 18-22 minutes, or until a toothpick inserted into the center comes out clean.

Cool the cupcakes in the muffin pans for 10 minutes.

Transfer cupcakes to wire racks to cool completely.

In a small bowl, beat mascarpone cheese, confectioners' sugar, and vanilla extract until smooth and creamy.

Frost the cooled cupcakes with the mascarpone frosting.

Store the frosted cupcakes in the refrigerator until ready to serve.