Pre-heat oven to 350°F Grease/spray a Bundt pan.
In a medium bowl combine the flour, cocoa, baking soda and salt. Set aside.
In a large bowl, beat the butter until fluffy. Add the sugar and continue beating until light and fluffy. Beat in vanilla and eggs until well combined. Add the dry ingredients and the wine, alternating and mixing well after each addition.
Spread the batter into the Bundt pan. Bake for 30-40 minutes, or until toothpick inserted in the center comes out clean.
Cool for 15 minutes then remove from pan. Cool completely before adding chocolate cream filling.
For Filling: In a large bowl, beat the butter until fluffy. Gradually add the sugar, beating well. Add the vanilla and cocoa. Beat in the milk until creamy.
Using a large serrated bread knife, carefully slice off the top half of the Bundt cake. Set aside the top. Using your fingers, press down on the center of the bottom of the cake to make a small "canal" or "moat" all around the bottom section of the cake.
Place the filling in a pastry bag. Fill the moat with the chocolate filling. Replace top half of cake. Dust top of cake with powdered sugar.
Note: I usually scoop out the cake from the bottom half rather then pressing down. Plus then I get to sample the cake!
Note: If you do not have a pastry bag use a large ziplock bag and after filling it with the chocolate cream cut off the corner and squeeze filling like you would with a pastry bag.