In a large skillet over medium heat, brown the ground beef until fully cooked. Drain excess fat.
Add the diced onion, bell pepper, and minced garlic to the skillet. Cook for about 5 minutes until the vegetables are softened.
Transfer the beef and vegetable mixture to a slow cooker. Add the black beans, corn, diced tomatoes, chili powder, cumin, salt, and black pepper. Stir to combine.
Cover and cook on low for 6 hours or on high for 3 hours.
About 30 minutes before serving, spread the frozen tater tots evenly over the top of the casserole. Cover and continue cooking until the tater tots are golden and crispy.
Sprinkle the shredded cheddar cheese on top during the last 10 minutes of cooking. Cover until melted.
Serve hot and enjoy!