Preheat oven to 350.

Cook rigatoni according to package instructions but undercook by about 3 minutes (it will continue to cook in oven). Drain pasta and return to pan.

While rigatoni is cooking, slice sausage. Heat oil or butter in large saute pan. . Add sausage and cook, stirring often until browned.

Stir ranch dressing, pesto, tomatoes and 1 C of the cheese into pasta. Stir in sausage.

Transfer mixture into a 9x13 baking dish. Top with remaining cup of cheese. Bake uncovered 20 minutes.

Enjoy!