Remove the foil and finish baking for another 20 minutes, this will lightly brown the top. Remove from the oven and let the Scalloped potatoes set for 10 - 15 minutes before serving.
I've followed several different recipes, but Half Baked Harvest, run by cookbook author Tieghan Gerard, has a recipe for cheesy scalloped potatoes with caramelized onions that has become a go-to ...