Prepare Cake: Preheat oven to 325°. Whisk together flour and next 3 ingredients. Beat 1 1/2 cups butter in a medium bowl at medium-high speed with an electric mixer until smooth. Gradually add granulated sugar, beating until light and fluffy. Add eggs, 1 at a time, beating just until yolk disappears. Combine 1 1/4 cups buttermilk and next 2 ingredients. Add flour mixture to egg mixture alternately with buttermilk mixture, beginning and ending with flour mixture. Beat at low speed after each addition. Fold in bittersweet chocolate morsels. Pour batter into a well-greased (with shortening) and floured 12-cup Bundt pan. Sharply tap pan on counter to remove air bubbles.
Bake at 325° for 1 hour and 15 minutes to 1 hour and 25 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 20 minutes. Remove from pan; cool completely on rack.
Prepare Chocolate Glaze: Combine semisweet chocolate morsels, 3 Tbsp. butter, and 1 Tbsp. corn syrup in a microwave-safe glass bowl. Microwave at MEDIUM (50% power) 1 to 1 1/2 minutes or until morsels begin to melt, stirring after 1 minute. Stir until smooth. Stir in 1/2 tsp. vanilla.
Prepare Buttermilk Glaze: Whisk together powdered sugar, 1 Tbsp. buttermilk, and 1/4 tsp. vanilla in a small bowl until smooth. Add up to 1 Tbsp. buttermilk, if desired. Drizzle warm glazes over cooled cake.
Mini Triple-Chocolate Buttermilk Pound Cakes: Prepare recipe as directed through Step 1, pouring batter into 2 lightly greased (with vegetable cooking spray) 12-cup Bundt brownie pans, filling each about three-fourths full. Bake at 325° for 26 to 30 minutes. Cool in pans on wire racks 10 minutes; remove from pans, and cool completely. Proceed with recipe as directed in Steps 3 and Makes 2 dozen. Hands-on 45 min.; Total 1 hour, 25 min.