My Cowboy Casserole Is a Southwestern Favorite

Name: My Cowboy Casserole Is a Southwestern Favorite
Ingredients: Nonstick spray; 2 tablespoons canola oil; 1 medium yellow onion , chopped (about 1 1/2 cups); 1 1/2 pounds 90/10 ground beef; 1 ( 1 - ounce ) envelope taco seasoning mix; 1 teaspoon garlic powder; 1/2 teaspoon kosher salt; 2 ( 15 - ounce ) cans pinto beans , drained and rinsed; 2 ( 10 - ounce ) cans diced tomatoes with green chiles; 1 cup frozen corn kernels; 1/2 cup sour cream; 1 ( 8 - ounce ) package shredded Mexican-blend cheese , divided (about 2 cups); 1 ( 32 - ounce ) package frozen potato tots; Chopped fresh cilantro , optional