Step 1: Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish. This prevents sticking and ensures easy cleanup for your cowboy casserole recipe.
Step 2: In a large skillet or Dutch oven, brown the ground beef over medium-high heat, breaking it up with a spoon. Once no longer pink, drain off any excess fat. Add the chopped onion and cook until softened, about 5 minutes. Stir in the minced garlic and cook for another minute until fragrant.
Step 3: Stir in the tomato paste and cook for 1-2 minutes, letting it caramelize slightly. Then, add the diced tomatoes (undrained), beef broth, Worcestershire sauce, chili powder, cumin, smoked paprika, salt, and black pepper. Bring the mixture to a simmer, then reduce heat and cook for 10-15 minutes, allowing flavors to meld and sauce to thicken. Stir in the corn and black beans (if using) and cook for 2-3 minutes more.
Step 4: Pour the beef and vegetable mixture evenly into the prepared baking dish. Sprinkle 1 cup of the shredded cheese over the beef mixture. Arrange the frozen tater tots in a single layer over the cheese, covering the entire surface.
Step 5: Bake for 25-30 minutes, or until the tater tots are golden brown and crispy. Remove from the oven, sprinkle the remaining 1 cup of shredded cheese over the tater tots, and return to the oven for another 5-10 minutes, or until the cheese is melted and bubbly. Let the cowboy casserole recipe rest for 5-10 minutes before serving. Garnish with fresh green onions or cilantro and a dollop of sour cream, if desired.