This is one of my mother's favorite ways to cook yellow summer squash. Her version includes a fair lot of cheese, and you could go that way if you have a bag of your preferred vegan cheese on hand. However, I decided to try a different direction:
Roast 5 medium summer squash, split in half, at 400 F for 30 minutes. Scoop out innards, mix with 1 T nutritional yeast, 1 t oregano, 2 T crushed cornflakes, salt and pepper to taste. (As the size of your squash may be different from mine, be sure to taste the filling and adjust seasonings as needed.) Refill squash. Top with more crushed cornflakes, return to oven for another 15 minutes. In the background, you can see roasted okra, just because the oven was on and there was room on the pan.