Tunnel of Fudge Cake

1 ¾ c. sugar
3 ½ sticks butter, softened
6 large eggs
2 c. powdered sugar
2 ¼ c. flour
¾ c. baking cocoa
2 c. chopped walnuts

Chocolate Glaze:
¾ c. powdered sugar
¼ c. baking cocoa
6-8 tsp. milk

Preheat oven to 350 and position a rack in the middle of the oven. In a large bowl with an electric mixer, beat the sugar and butter together on medium speed until light and fluffy. Add the eggs, one at a time, beating well after each addition. Gradually beat in the powdered sugar. Stir in flour, cocoa, and nuts until well blended.
Spoon the batter into a greased bundt pan and smooth the top. Bake for 45-50 minutes, or until the top is set and the edges are beginning to pull away from the sides of the pan (this cake has a soft center, so testing with a toothpick will not work).
Cool the cake in the pan on a wire rack for 1 ½ hours, then invert onto a serving platter and cool for at least 2 hours.
To make the glaze: In a small bowl, stir together all the ingredients, adding enough milk to achieve a drizzling consistency. Spoon over top of the cake, allowing some to run down the sides.