What's so great about stuffed croissants is that you can mix and match your flavors. I started making these golden beauties with frozen blackberries, a bit of sugar, and cream cheese. Then I tried cream cheese, cinnamon, and walnuts. I've brushed the crust with egg whites before, though I usually go without this extra step. Stuffed croissants are customizable to everyone's individual tastes and you'll want to experiment every Sunday until you find your family's favorite.