Step 1: Cook the Ground Beef

1. Heat a large skillet over medium heat.
2. Add the ground beef and cook until browned, breaking it into small pieces with a spatula.
3. Drain excess grease and stir in the taco seasoning. Add a splash of water and simmer for 2-3 minutes. Set aside.

Step 2: Prepare the Burrito Fillings

1. In a mixing bowl, combine the cooked rice, nacho cheese sauce, diced tomatoes, shredded lettuce, sour cream, and diced onions.
2. Mix well to ensure all ingredients are evenly distributed.

Step 3: Assemble the Burritos

1. Lay a flour tortilla flat on a clean surface.
2. Spread a layer of the beef mixture in the center of the tortilla.
3. Top with the rice and cheese mixture.
4. Fold the sides of the tortilla inward, then roll it tightly from the bottom to form a burrito.

Step 4: Add the Grilled Cheese Layer

1. Heat a griddle or non-stick pan over medium heat.
2. Sprinkle a generous amount of shredded cheddar and Monterey Jack cheese onto the griddle.
3. Place the burrito seam-side down onto the melted cheese.
4. Press gently with a spatula and let it cook for 1-2 minutes until the cheese is golden and crispy.

Step 5: Serve and Enjoy

1. Carefully remove the burrito from the griddle using a spatula.
2. Let it cool for a minute, then slice it in half if desired.
3. Serve with extra sour cream, salsa, or guacamole on the side.