Bring a large pot of salted water to a boil over high heat. Cook the pasta until al dente. Reserve 1 cup of the pasta water, then drain and add it back to the hot pot.
Meanwhile, heat the olive oil in a large skillet over medium heat. Add the zucchini, squash, and tomatoes. Season with salt and pepper. Cook stirring occasionally, until the vegetables are soft and light golden brown, 8-10 minutes.
Stir in the butter, garlic, oregano, and any additional seasonings you'd like. Cook until the butter is melted and the herbs are fragrant, 2-3 minutes. Remove from heat and dump the vegetables into the pot of pasta.
Add the basil pesto and parmesan cheese, tossing until the cheese is melted. Add the reserved pasta cooking water, 2 tablespoons at a time, as needed... until it has reached your preferred sauce consistency. Stir in the basil to wilt.
Serve immediately with a squeeze of lemon juice and fresh basil.
Notes
Recipe adapted from Tieghan's Everyday Half Baked Harvest cookbook.