Directions. 1  Preheat oven to 450. 2  Grease roasting pan with olive oil. 3  Chop zucchini and yellow squash and put into large bowl. 4  Drizzle olive oil over squash. 5  Pour squash into roasting pan and spread it out until it evenly covers the pan. 6  Bake 15 to 20 minutes, stirring once until cooked through. Preheat oven to 450. 2  Grease roasting pan with olive oil. 3  Chop zucchini and yellow squash and put into large bowl. 4  Drizzle olive oil over squash. 5  Mix with a large spoon until squash is evenly coated.