Preheat your oven to 400°F and line a large sheet pan with parchment paper or foil for easier cleanup.
In a small bowl, whisk together the olive oil, garlic powder, and Italian seasoning until well combined.
2 tablespoon olive oil, 1 teaspoon garlic powder, 1 teaspoon Italian seasoning
Add the sliced zucchini and yellow squash to a large mixing bowl. Drizzle with most of the seasoned oil and toss until everything is evenly coated.
10 ounces zucchini (about 1 small), 10 ounces yellow squash
In another bowl, toss the halved cherry tomatoes with the remaining oil. This helps keep the tomatoes juicy without making the other vegetables watery.
7 ounces cherry tomatoes
Spread all the vegetables out in a single layer on the baking sheet. Try to leave a little space between them so they roast properly instead of steaming.
This is where people usually go wrong. If the pan is overcrowded, the vegetables release too much moisture and you lose those golden roasted edges.
Sprinkle everything with salt and black pepper, then scatter the Parmesan evenly over the top.
salt + black pepper, ½ cup finely shredded Parmesan cheese
Bake for 25–30 minutes until the zucchini and squash are tender, the tomatoes look juicy and jammy, and the Parmesan is melted and lightly golden around the edges.
The vegetables should look roasted and slightly caramelized, not pale or watery.
Top with fresh parsley or basil before serving if using. I like serving this warm while the Parmesan is still slightly melty and the tomatoes are extra juicy.
fresh or dried parsley or basil