Biscuit layer. In a bowl combine Bisquick baking mix and 8 ounces of water and stir together until well mixed to make the biscuit dough. Spread the biscuit dough over the bottom of the baking dish and pat it out so it covers the entire bottom of the dish. Set aside.
Meat. Add the ground beef to the pan and cook until it is browned. Remove the ground beef from the heat and drain off any excess grease. Then return the ground beef mixture to the skillet and add the taco seasoning and Rotel diced tomatoes with chilies (undrained). Stir together and continue to cook for 5 minutes.