Preheat the oven to 350°F (175°C) and spray a 9x13-inch baking pan with cooking spray.
In a large skillet over medium-high heat, brown the ground beef until no pink remains, breaking it up with a spoon.
Add the diced red bell pepper and chopped onion to the skillet and cook about 3 minutes until softened; drain any excess grease.
Stir in the taco seasoning, Rotel diced tomatoes, drained black beans, drained corn, and salsa.
Add the softened cream cheese to the skillet and stir until it melts and the mixture is smooth and combined; remove from heat.
Place 5 tortillas in the bottom of the prepared pan, overlapping as needed. Sprinkle about 1/2 cup of shredded cheese over the tortillas.
Spread half of the beef and bean mixture evenly over the cheese layer.
Place the remaining 5 tortillas over the first layers, then top with the rest of the beef mixture.
Finish by sprinkling the remaining shredded cheese evenly over the top.
Bake for 25–30 minutes until the casserole is hot and bubbly and the cheese is melted.
Remove from the oven and top with any desired toppings before serving.