For thicker cookies, chill dough for 30 minutes to 1 hour before baking; avoid chilling longer to prevent marshmallows from breaking down., Store fully cooled cookies in an airtight container at room temperature for up to 5 days. Marshmallows will soften over time but flavor remains., Freeze dough balls in a freezer-safe bag for up to 3 months; bake from frozen, increasing baking time to about 12 minutes., When making a smaller batch, halve the ingredients and use one egg yolk instead of whole egg and yolk., Mix-ins like ½ cup white chocolate chips or St. Patrick’s Day sprinkles can be added for variation., Add green food coloring (start with ¼ teaspoon) for festive color., Drizzle with Bailey’s glaze or sandwich with frosting for additional flavor.