Preheat oven to 325°. Spray 2 molds of 12-cup Bundt brownie pans with cooking spray and set aside.
Whisk together flour and next 3 ingredients, set aside.
In the electric mixer bowl, beat 1 1/2 cups butter at medium-high speed until smooth. Gradually add 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 and pour batter into pans, filling each about three-fourths full.
Bake at 325° for 25 to 30 minutes. Cool in pans on wire racks 10 minutes; remove from pans, and cool completely.
Drizzle with Chocolate Glaze