Mexican Cornbread Casserole

For the filling:

• 1 medium onion (finely chopped)
• 1 bell pepper (finely chopped)
• 2 tablespoons olive oil
• 1 pound ground beef
• 3 tablespoons taco seasoning (equivalent of 1 packet)
• 1 (15 ounce) can southwest style corn (drained)
• 1 (8 ounce) can tomato sauce
• 1 (4 ounce) can diced green chiles
• 1 (10 ounce) can dice tomatoes with green chiles (like Rotel)
• salt and pepper to taste
• 1 cup shredded cheese (cheddar or Mexican blend)

For the cornbread:

• 1 (8 ounce box) Jiffy corn muffin mix
• 1 large egg
• 1 cup sour cream
• 1 (15 ounce) can creamed corn
• 2 cups shredded cheese (cheddar or Mexican blend) Divided

Optional toppings:

• sour cream
• Diced avocado
• cilantro
• shredded cheese
• diced tomatoes
• green onion