Mix together all ingredients and refrigerate until needed.
Make shells according to instructions minus one minute. Use plenty of water in pot. Add salt to water before putting shells in. Drain immediately. Allow to cool before filling.
Preheat oven to 375 degrees F. (190 C.)
If you don't have a pastry bag, use a plastic baggie (food safe) and cut a hole in tip. Do not over-fill. You should be able to close the shell. If using pastry bag, only fill it half-way. You can also spoon in your ricotta cheese, using a small spoon.
Once all the shells are filled, layer tomato sauce on a baking dish. Place each filled shell in pan. Cover with more sauce.
Add mozzarella cheese.
Cover completely with foil and bake for 30 minutes or until all cheese is melted. You can take off the foil and bake for another five minutes, but I cover with foil to keep the edges of shells from burning.