Preheat oven to 350°F (175°C).
Prepare the Spanish rice mix in a saucepan according to package directions using the butter, water, and the full can of diced tomatoes. Set aside.
In a large skillet, cook ground beef over medium heat until browned. Drain excess grease.
To the skillet with the beef, add the cooked Spanish rice and 1 ¼ cups of the enchilada sauce. Stir to combine. Remove from heat.
Warm the tortillas until pliable (microwave in a damp towel for 30-45 seconds).
Spread ½ cup of the remaining enchilada sauce in the bottom of an ungreased 13x9 inch baking dish.
For each enchilada: Place a warmed tortilla on a work surface. Spoon about ⅔ cup of the beef rice filling down the center. Top with 1 tbsp of shredded cheese. Roll up tightly and place seam side down in the baking dish.
Pour the remaining enchilada sauce over the rolled enchiladas. Sprinkle with the remaining cheese.
Bake, uncovered, for 20-25 minutes until the cheese is melted and bubbly.
Let cool for 5-10 minutes before serving. Garnish with optional toppings as desired.