After 20 minutes, remove the baking sheet with potatoes from oven. Gently loosen the potatoes from the baking pan with a metal spatula to prevent sticking. Add the squash to the baking sheet evenly over the entire pan. Use the spatula to work the squash into the pan evenly and in a single layer with the potatoes. Return to oven. Cook for an additional 15-20 minutes or until potatoes are golden brown and zucchini is easily pierced with a fork. Transfer to a tray. Add salt and pepper, if needed. Serve warm.