Preheat oven to 450°F (230°C). Melt 1/4 cup butter and pour it into an 8" square or 9"x7" rectangular baking dish; set the dish aside.

In a large mixing bowl, whisk together 2 cups all-purpose flour, 1 tablespoon baking powder, and 1 teaspoon salt.

Add 1/3 cup shortening to the flour mixture and cut it in with a fork or pastry cutter until the mixture resembles coarse crumbs.

Add 1/2 cup sour cream and stir with a wooden spoon until combined.

Add 1/2 cup 7-UP (room temperature) and stir until the dough is sticky and shaggy.

Lightly flour a work surface. Turn the dough out onto the floured surface and gently pat or roll it into a roughly square or rectangle about the same size as your prepared baking dish. Do not overwork the dough.

Using a bench scraper, knife, or pizza cutter, cut the dough into evenly sized biscuits by cutting all the way through the dough.

Transfer the cut biscuits into the buttered baking dish, arranging them as desired. If any melted butter remains in the bowl or measuring cup, spoon it over the biscuits.

Bake in the preheated oven for 16 to 18 minutes, or until the tops are golden brown.

Remove the dish from the oven and let the biscuits cool for a few minutes before serving.