To make the white sauce, In medium saucepan, combine cornstarch, salt and pepper; using wire whisk, stir in milk until smooth. Add margarine. Stirring constantly with rubber spatula, bring
to boil over medium-high heat and boil 1 minute. Remove from heat. Cool slightly and add cheddar cheese. Stir until melted.
To make filling, combine browned beef, browned sausage, sautéed onion and Cheese Sauce. Cool until thickened. Cook cannelloni as directed, but cook
for only 3/4 recommended time; rinse and drain. Fill cannelloni with filling mixture and pack firmly into greased baking dish.
Pour marinara sauce generously over cannelloni.
To Freeze: Pack into a pan that can go from the freezer to the oven. Secure it with plastic wrap and foil.
To Reheat: uncover and bake FROZEN casserole in 400-degree oven for 1 hour, or until hot and bubbling. Sprinkle
with parmesan cheese, return to oven for 5 minutes to brown top.