Preheat oven to 350F. Grease a 12-cup bundt pan and set aside.
In a medium bowl sift flour, cocoa powder, baking powder, and salt. Set aside.
In a mixer bowl fitted with the paddle attachment, beat together butter, sugar, and egg on medium-high speed for 3-4 minutes until combined. Scrape down the sides and bottom of the bowl as necessary.
Add vanilla extract. Using a spatula, fold the flour mixture in 3 additions, alternating it with the wine in 2 additions (starting and ending with the flour). Add the milk and combine. Do not overmix.
Scrape the batter into the prepared pan and smooth the top. Bake for 45 minutes or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for 10 minutes on a wire rack, then turn it out and let it cool completely. Drizzle the cake with chocolate ganache.
Chocolate ganache: Place chocolate in a medium heatproof bowl; set aside.
Place cream in a small saucepan over medium heat and bring to a simmer. Pour over chocolate and let stand until chocolate has softened, about 5 minutes.
Add butter and stir until smooth. Let cool slightly before using.