Heat oven to 325 F. Grease and flour Bundt pan and tunnel.
In a medium mixing bowl, sift together flour, cocoa, baking powder and salt. Set aside.
In the bowl of a stand mixer, on medium speed, cream together sugar, butter, eggs and vanilla until light and fluffy, about 3 minutes. Reduce speed to low. Alternately mix in milk and flour mixture, beginning and ending with milk.
Pour batter into the prepared pan. Place tunnel in center of Bundt pan. Bake in for 65 to 70 minutes, or until toothpick comes out clean. Allow to cool in pan for ten minutes. Remove from pan and cool completely on a cooling rack.
Return cake to pan and refrigerate until ready to serve.
Ice Cream Filling
In a medium mixing bowl, whisk together eggs, sugar and vanilla. Stir in cream. Pour mixture into the freezer bowl of ice cream maker. At the end of the freezing process, add chocolate and allow the paddle to rotate for 3 to 5 turns, or until chocolate is stirred through out.
Dark Chocolate Glaze
In a saucepan over medium heat, bring cream and butter to a simmer. Place chocolate in the bowl of a food processor. With machine running, gradually pour in the cream and vanilla and process until smooth and thickened, about 3 minutes. Drizzle over cake immediately.
Just before serving, fill tunnel with ice cream filling. Invert cake onto serving platter. Drizzle with Dark Chocolate Glaze. Serve.