Preheat oven to 325°F. Butter and flour a 12 cup Bundt pan or spray with baking spray. Set aside. (Alternately, you may use an angel food tube pan.)
Using an electric mixer, cream together butter, shortening and sugar. Beat for 2 minutes or until fluffy. Add vanilla, lemon and almond extracts. Whip again until combined.
Lower the speed of the mixer and add eggs one at a time beating well after each addition.
In a separate bowl, use a whisk to sift together flour, baking soda and salt. Lower the speed of mixer, adding dry ingredients alternately with buttermilk beginning and ending with flour. Stop and scrap the sides of the bowl periodically.
Pour evenly into pan. Place into the oven and bake for 80-90 minutes or until a toothpick or cake tester inserted into the center comes back clean.
Cool in the pan for 30 minutes, then invert and remove from pan to a cooling rack to cool completely. Once cooled, dust with powdered sugar or drizzle with glaze.
Store in an airtight container chilled for 5-7 days or if unglazed, you can store it at room temperature for up to 3 days.
To make optional glaze: In a small bowl mix together powdered sugar, buttermilk and vanilla until sugar has dissolved. Drizzle over cooled cake.