6ozchopped fresh kale(about 3 cups; I use half of a 12-oz bag that I get at Whole Foods)
Preheat your oven to 400 degrees F. Lightly grease a 9 X 13-inch baking dish.
In a large, deep skillet, heat the olive oil over medium-high heat, about 2 minutes.
Add the ground beef. Cook, stirring to break up and crumble the beef, until no longer raw, about 5 minutes.
Lower the heat to medium. Stir in the salt, pepper, garlic powder, onion powder, and oregano.
Stir in the marinara sauce.
In batches, stir the kale into the mixture, cooking just until it slightly wilts.
Turn the heat off. Stir 4 oz of the cheese into the mixture.
Transfer the mixture to the prepared baking dish. Sprinkle the remaining 4 oz of cheese on top.
Bake until hot and bubbly, 10-15 minutes. If your baking dish is broiler-safe, you can broil the casserole instead of baking. Broil 6 inches below the heating element (not directly under), 2-3 minutes, or until the cheese has melted.
Instead of cooking on the stovetop then transferring the mixture to a baking dish, you can use a stovetop-and-oven-safe Dutch oven for both the stovetop cooking and the baking.