Cake
1 cup flour
1/2 cup Dutch-process cocoa
1/2 teaspoon salt
1/4 teaspoon baking powder
1/4 teaspoon baking soda
1/2 cup room temperature buttermilk
1 teaspoon vanilla extract
10 tablespoons softened butter
1 1/3 cups sugar
3 beaten eggs
Glaze
3 tablespoons butter
1/3 cup heavy whipping cream
1/3 cup sugar
1/3 cup Dutch-process cocoa
pinch salt
1/2 teaspoon vanilla extract

Cake
Heat oven to 350°F. Spray 6 cup Bundt pan with nonstick cooking spray. Combine flour, cocoa, salt, baking powder and baking soda. Sift and set aside. Combine buttermilk and vanilla. Beat butter till creamy. Slowly add sugar. Beat 4-5 minutes till light and fluffy. Reduce speed to medium and slowly add eggs, beating constantly. Alternately add flour mixture and buttermilk mixture, beginning and ending with flour. Beat only enough to incorporate ingredients after each addition. Spread evenly in prepared pan. Bake 45-55 minutes till toothpick inserted in center comes out clean. Cool in pan on rack 10 minutes. Invert onto rack to cool completely.
Glaze
Melt butter in saucepan. Add cream, sugar, cocoa and salt. Mix well. Cook over medium heat till mixture is smooth and hot but not boiling, whisking constantly. Remove from heat and stir in vanilla. Chill 15-20 minutes till slightly thickened. Pour glaze over cake and let stand till firm.
Note
Cake can also be made in 11x7 inch baking dish. Bake 40-45 minutes.