In a large skillet, brown and crumble the ground beef. Stir in the water and taco seasoning and simmer until heated through. Set aside.
Preheat oven to 350 degrees. Pour about half a cup of enchilada sauce in the bottom of a 12 inch round casserole dish or 9x13 baking pan.
Place a tortilla shell into the casserole dish. Using a rubber spatula or back side of a spoon, evenly spread a third of the refried beans onto the tortilla. Add a layer of the sour cream.
Continue to layer the casserole, next with a portion of the seasoned ground beef, then the tomatoes, onions, jalapeno, sauce, and cheddar cheese.
Repeat two more times, then top with a final tortilla, sauce, and cheese.
Bake uncovered for 45 minutes. Remove from the oven and let stand 15 minutes before serving.
Notes
For this recipe, we used a round 12-inch casserole dish. If you use a rectangular dish, you can cut the tortillas to fit, or may require more tortillas to finish the layers.