In a medium to large pot, saute onions and peppers until they soften.
Add zucchini, squash, and chipotle or Italian veggie sausage if using. Saute until soft, then add mushrooms. Saute until mushrooms release their liquid.
Add fresh minced garlic and saute for no more than one minute.
Add whole tomatoes, tomato paste, and fire roasted tomatoes.
Add salt, pepper, basil, oregano, and crushed red pepper, if using.
Reduce heat to medium low, and let sauce simmer. Stir every few minutes.
While your sauce is simmering, combine sour cream and ricotta in a small bowl. Whisk to combine.
Set a large pot of boiling water on your stove, and prepare your spaghettin noodles according to package directions.
Preheat oven to 350 degrees.
After about 20 minutes, or once the tomateos in your sauce have started to break apart you sauce should look sauce like - though you can leave it chunkier if your prefer. Alternatively, you may cook it longer for a thinner sauce.
Toss spaghetti noodles with the sauce.
Layer half of the noodles in the 9x13 pan.
On top of your half, use a spoon and spread the sour cream/ricottta mixture. Then top with half of your mozzarella and mixed cheese blend.
Place the remaining half of your noodles on top of the cheese and sour cream/ricotta layer.
Finish by topping the final layer with your remaining sour cream and ricotta, and your remaining cheeses.
Sprinkle the top with a little more basil and oregano. At this point, the spaghetti can be refrigerated until the next day, or you can put it right into the oven.
Bake at 350 until heated through, and the top is golden brown and bubbly.