Preheat oven to 400 degrees. Oil a 9 x 13 baking dish.
Cook pasta according to package directions. Do not over cook. Slightly under-cooked is ok. Drain and set aside.
Meanwhile, saute onion in olive oil on medium heat until beginning to become translucent. Add garlic and red pepper and saute a minute more. Add sausage and saute until mostly cooked. Add zuchinni and seasonings and cook, stirring, 3 minutes. Add cream cheese, tomatoes, pasta, and ketchup and cook, stirring continually until cream cheese is melted.
Pour mixture into baking dish. Top with shredded cheese and bake until cheese is melted and to desired consistency. (just-melted, bubbly, golden brown, toasty, etc) about 10-25 min