Awesome Light and Fluffy Biscuits

8 Tablespoons unsalted butter
4 Tablespoons Vegetable Shortening
3 Cups all-purpose flour
1 Tablespoon sugar
1 Tablespoon baking powder
1 Teaspoon salt
1/2 Teaspoon baking soda
1 1/4 cups buttermilk

1. Chill Fat: Cut butter and shortening into 1/2 inch pieces and refrigerate until chilled. 
2. Mix Dough: Pulse flour, sugar, baking powder, salt, and baking soda in food processor until combined. Add chilled butter and shortening and pulse until mixture resembles coarse mail.
3. Knead Dough. Transfer flour mixture to large bowl. Stir in buttermilk until combined. Turn dough onto lightly floured surface and knead briefly, 8 to 10 times, to form smooth, cohesive ball. Roll dough into circle about 3/4 inch think. 
4. Cut Biscuits.
5. Bake Biscuits at 450 until biscuits begin to rise - about 5 min. Reduce heat to 400, turn biscuits and finish cooking until golden brown, 10-12 more minutes. 

*America's Test Kitchen