Preheat oven to 400°F.

In large bowl, stir together flour, baking soda, baking powder and salt. Cut in reserved chilled bacon fat and 3 tablespoons solid vegetable shortening until it resembles coarse meal. Stir in cheddar cheese and crumbled bacon, then add buttermilk. Stir until dry ingredients are just moistened (mixture may be slightly lumpy).

Transfer dough to lightly floured surface and knead several times until it just holds together.

With lightly floured hands, pat dough out 1/2 inch thick. Flour 2-inch round biscuit cutter and cut out biscuits, placing them 2 inches apart on ungreased baking sheet. Gather up scraps, pat out again and cut out more biscuits.

Bake 15 minutes, or until biscuits are lightly browned. Transfer to wire rack and serve warm or at room temperature.