Add ground beef. Cook until done, meat should be crumbly.
Add Rotel. Mix well.
Remove from heat and stir in ricotta cheese.
Divide meat mixture evenly between the cooked pasta shells. Stuff them into the shells gently with a spoon.
Place stuffed shells onto a 9×12 baking pan or casserole.
Pour Ragu sauce over all the shells.
Sprinkle mozzarella cheese evenly over the sauce.
Bake in a 350 degree oven for 30 minutes or until the cheese has melted and starts to brown.
If making this dish in advance put everything except the mozzarella cheese into the casserole, cover and store in the fridge. Sprinkle the cheese just before you bake it. Refrigerated shells will take about 10-15 minutes longer to bake.
Store leftover shells in a tightly sealed container in the fridge. Reheat in the microwave.