Preheat oven to 350°

Prepare rice according to package directions. Set aside.

In a small skillet, heat butter over medium high heat. Add onion and sauté 1-3 minutes, just until softened and fragrant.

To a medium mixing bowl, add the cooked rice, sautéed onions, corn, salsa, sour cream, and chili powder. Fold in cheese. Adjust seasoning to taste.

Pour rice mixture into a prepared 8x8 baking dish.

Bake, uncovered 35-40 minutes.