01 - Preheat oven to 375°F. Lightly grease a 9x13 inch baking dish with cooking spray or butter.
02 - In a large skillet over medium heat, cook ground beef and chopped onion until beef is browned and onion is softened, about 6–8 minutes. Drain excess fat from the skillet.
03 - Stir in garlic powder, onion powder, kosher salt, and black pepper. Mix well to distribute seasonings evenly.
04 - Pour condensed cream of mushroom soup and milk into the skillet. Stir until fully combined and smooth. Add frozen corn and peas, mixing to incorporate.
05 - Transfer the beef and vegetable mixture to the prepared baking dish, spreading it into an even layer. Sprinkle shredded cheddar cheese evenly over the top.
06 - Arrange frozen tater tots in a single, tightly packed layer over the entire surface of the casserole.
07 - Bake uncovered for 40–45 minutes, until tater tots are golden brown and crispy, and the filling is bubbling around the edges.
08 - Let the casserole rest for 5 minutes before serving to allow the layers to set for easier scooping.