Butter. Start by preheating your oven to 425. Place your butter into a 9X13" baking dish and then place the baking dish into your oven for the butter to melt. Keep an eye on the melting butter when you move on to the next couple of steps as you will need to remove the baking dish from the oven when the butter has melted.
Combine. While the butter is melting, in a mixing bowl, combine together the remaining ingredients (baking mix, soda, and sour cream) until the dough is able to hold together and is 'sticky'.
Dough. Lightly dust a clean work surface with additional bisquick and then transfer your dough to the work surface. Turn the dough a few time, adding a small amount of additional mix as needed for the sticky dough. When you are able to do so (the dough is workable), gently press the dough into a large circle that is about an inch thick.
Cut. Use a round cookie cutter or biscuit cutter to cut out 12 biscuits.
Bake. Place each of the biscuits into the baking dish with the melted butter. Bake the biscuits for 10-12 minutes or until the tops turn a golden brown.
Set. Let your biscuits set in the baking dish while absorbing any remaining melted butter before serving.