Preheat your oven to 450°F (230°C).
Melt your stick of butter and set it aside to cool slightly.
In a large mixing bowl, combine the 4 cups of baking mix.
In a separate bowl, whisk together the sour cream and 7-Up until well combined.
Pour the sour cream and 7-Up mixture into the bowl with the baking mix, and gently stir until just combined.
Drizzle in the melted butter and fold it into the mixture until no dry spots remain.
On a floured surface, turn out the dough and pat it into a rectangle about 1-inch thick. Cut into squares or use a biscuit cutter.
Place the biscuits on a baking sheet lined with parchment paper and bake for 10-12 minutes or until golden brown on top.
Remove from the oven and brush the tops with any remaining melted butter. Serve warm.
