Heat olive oil in a skillet over medium heat until shimmering. Add onion and cook about two minutes, then add bell pepper and garlic and saute another 5 minutes, stirring occasionally.
Remove from heat and let cool a bit while you cut up the squash, then add turkey, egg, Italian seasoning, oregano, thyme, and sea salt to a large bowl. Add cooked onion & pepper mixture and combine, being careful not to overmix.
Preheat oven to 400 degrees, line two rimmed baking sheets with parchment paper (both the meatballs and veggies are messy; don't skip it), and spray each with cooking spray. Roll turkey mixture into 12 large meatballs and space evenly across one baking sheet. Spread squash, zucchini, garlic, and tomatoes in as close to a single layer as possible across the second baking sheet and toss with olive oil, sea salt, pepper, and Italian seasoning, then top with Parmesan.
Put both pans in the oven and bake at 400 degrees for 23 minutes, switching baking racks and stirring veggies halfway through, or until meatballs are cooked through and squash is tender.
Meanwhile, cook pasta al dente according to package directions. (Start the water boiling about the same time you put the meatballs and veggies in the oven, and the timing should work out pretty closely.) Drain, reserving about one cup of the starchy cooking liquid, then return pasta to the pot.
Toss hot pasta with Parmesan, lemon juice, crushed red pepper, and about 1/4 cup of cooking liquid until cheese is melted and noodles are coated with a very light sauce, adding additional pasta water to thin out as necessary.
Stir in cooked veggies (scrape in the whole pan, including the cheese and juice from where the tomatoes burst), then serve your veggie pasta topped with turkey meatballs and additional Parmesan to taste.
I had small yellow squash and medium zucchini, so used three summer squash + one zucchini -- the ratio isn't all that important; use what you have! You might notice that the pasta/meatball ratio is a little off here: You get a lot of pasta, but just 12 meatballs. This is a feature, not a bug, because on the first night everyone enjoys meatballs over their warm pasta -- and on the next night, you can serve the leftover veggie pasta cold as a hearty side dish.
Summer Squash Parmesan Pasta + Turkey Meatballs from Mashup Mom: https://www.mashupmom.com/summer-squash-parmesan-pasta-turkey-meatballs/