Preheat oven to 350°F.
Heat a large nonstick skillet over medium-high. Add ground beef, salt, and pepper and cook, stirring occasionally, until beef is lightly browned but not cooked through, 5 to 7 minutes.
Add onion and garlic; cook, stirring occasionally until onion is softened, about 5 minutes.
Add tomato paste, and continue cooking, stirring constantly, until fragrant, about 1 minute.
Reduce heat to medium-low, and stir in diced tomatoes, cream of mushroom soup, Dijon mustard, Worcestershire, and 1 cup of the Cheddar cheese until combined.
Remove skillet from heat and fold in rice.
Transfer to a 13- x 9-inch baking dish, spreading in an even layer.
Sprinkle top evenly with Monterey Jack cheese and remaining 1 cup Cheddar cheese.
Bake in preheated oven until cheese is melted and beginning to brown, 20 to 25 minutes.
Let sit 10 minutes before garnishing with parsley and serving.
