Refrigerate the peanut butter cookie dough for at least 30 minutes before spreading into the pan—this prevents it from rising too much and keeps the layers distinct and chewy rather than cake-like.

Let your marshmallow fluff sit at room temperature for 15 minutes before spreading, making it easier to apply evenly without tearing the delicate peanut butter layer underneath.

Use slightly more brown sugar than granulated sugar in your peanut butter base—the molasses adds moisture and depth, preventing the bars from drying out during baking and creating that signature chewy texture.

Bake only until the marshmallow is set but still slightly jiggly in the center (check at 20 minutes)—overbaking causes it to deflate and become dense rather than fluffy and gooey.

Allow bars to cool to room temperature, then refrigerate for at least 2 hours before cutting—this helps the marshmallow set properly and prevents the layers from sliding apart, giving you clean, professional-looking portions.