Creamy Penne Primavera

Preheat the oven to 325 degrees F (165 degrees C). Butter a 9x13-inch baking pan.

Bring a large pot of lightly salted water to a boil. Add penne and cook, stirring occasionally, for 9 minutes.

While pasta cooks, place cream cheese into a medium saucepan over medium heat. Add 1/2 of the Italian salad dressing, mayonnaise, sour cream, and milk. Whisk until creamy and melted, 3 to 4 minutes. Add 1/2 of the Parmesan cheese; whisk cheese sauce again until creamy, 3 to 4 minutes. Reduce heat to low.

Place spinach in a microwave-safe bowl and microwave on high power until soft, about 2 minutes. Transfer to a cutting board and chop.

Heat oil in a skillet over medium-high heat. Add mushrooms, onion, and garlic; saute until soft, 5 to 7 minutes. Reduce heat to low and keep warm.

Drain the pasta, rinse the pot, and return pasta to the clean pot.

Stir cheese sauce into pasta until coated. Add cooked spinach and onion mixture; stir. Add red bell pepper and remaining Italian dressing. Season with paprika, salt, and pepper. Stir well. Pour into the prepared baking pan. Top with remaining Parmesan cheese.

Bake in the preheated oven until bubbly and cheese is melted, about 30 minutes.