Preheat oven to 350F. Line a 9-in loaf pan with parchment paper. Set aside
In a large bowl with a handheld electric mixer, beat butter and sugar together until completely smooth and creamy. Beat in vanilla, melted chocolate, and and eggs one at a time, beating well after each addition. Beat in milk. Slowly beat in flour, cocoa powder, baking powder, and salt until smooth. Set aside for a moment.
Mint Cheesecake
In a medium bowl with a handheld electric mixer, beat cream cheese and sugar together until smooth. Add mint extract and food coloring (if using) and beat until smooth and creamy.
Scrape half of pound cake batter into prepared pan. Drop half of cream cheese on top of pound cake batter by the tablespoon, then top with remaining pound cake batter. Top with remaining cream cheese mixture. Use a knife to gently swirl batter and cream cheese several times.
Bake pound cake at 350F 55-60 minutes or until toothpick tests done. Let cake cool in pan 20 minutes then invert onto a cooling rack to cool completely. Dust top of pound cake with powdered sugar and slice. Enjoy!