Whisk together the flour, baking powder, sugar and salt in a large bowl. Cut in the shortening with a pastry blender. I just use the edge of a large spoon to do this until the mixture resembles coarse crumbs.
Use the same amount of this mixture as you would Bisquick in a recipe. Store in an airtight container. I put mine in the refrigerator especially if you use butter instead of lard or shortening.
I would use the unsalted butter since you have salt already in the recipe. You could also double this recipe. This will keep 3 to 4 months. Makes 7 1/2 to 8 cups.