Cream shortening and butter; gradually add sugar, beating well at medium speed with an electric mixer. Add eggs, 1 at a time, beating after each addition.
Sift flour, baking powder, salt, and cocoa together. Add to creamed mixture alternately with the milk, beginning and ending with the flour mixture. Mix just until blended after each addition. Stir in vanilla.
Pour batter into a greased and floured 10 inch tube pan. Bake at 350 degrees for 1 hour and 15 minutes or until a wooden pick inserted in the center comes out clean. Cool in the pan for 10 to 15 minutes; remove from the pan, and cool completely on a wire rack.
Spoon Chocolate Glaze over the top of the cake, allowing it to drizzle down the sides of the cake. Sprinkle top of cake with chopped pecans, if desired.
FOR THE CHOCOLATE GLAZE:.
Microwave the chocolate baking squares in a large glass bowl at high for 1 1/2 minutes, or until melted, stirring twice. Add sugar and water, beating at medium speed with an electric mixer until blended. Add egg, and beat until blended. Add egg yolk, and beat until mixture cools. Add butter, 1 tbsp at a time, beating until blended. Serve over cake.