Sauteed summer squash

I love summer squash. I've adapted this recipe from Ina Garten. I don't remember which cookbook it is in, but it is on page 120, I remember that.

4 zucchini
4 yellow squash
2 onions
olive oil
salt
pepper
grated Parmesan (not the green can--as Ina says)

Remove ends of squash, slice lengthwise, then slice 1/2 inch thick. Slice onions.

Heat 2T olive oil in 10-inch skillet. Cook onions in oil until lightly browned. Add half of squash and cook until tender. Remove to bowl and keep warm. Add a little more olive oil and cool remaining squash. Add to bowl. Season with salt and pepper to taste and stir with 1/2 C Parmesan.