Heat oven to 350°F. Spray large nonstick skillet with nonstick cooking spray. Heat over medium-high heat until hot. Add beef and onion; cook and stir 3 to 4 minutes or until browned.
Add seasoning mix, rice and water; mix well. Bring to a boil. Reduce heat; cover and simmer 5 minutes.
Remove skillet from heat; stir in kidney beans and tomato. Divide mixture evenly into 4 ungreased 2-cup individual casseroles. Top each with cheese; sprinkle with chili powder.
Bake at 350°F. for 10 to 15 minutes or until casseroles are thoroughly heated and cheese is melted.