Preheat oven to 375, and melt 1 stick of butter (1/2 C) in a 9x13 dish, and set-aside for biscuit dough. Mix flour, powder, salt and soda. Cut in 1/4 C salted butter until evenly crumbled, add COLD sour cream & 7-Up, and mix til just combined. Turn out dough onto a lightly floured surface & knead it 2-3 times. Shape into a rectangle about the size of a 9x13 dish, about 1 1/2" thick. Using a knife or dough cutter, cut into (3x4) 12 biscuits. Place them into melted butter in the baking dish. Bake 15 minutes, or til golden brown. Serve with sausage gravy or butter & honey.