Step 1

Lightly grease a 9-inch square baking pan with nonstick cooking spray and set aside.

Step 2

Open the bag of chips and crush them down until you have a little less than 6 cups.

Step 3

Place a large saucepan over low heat and add in the butter and 4 cups of the marshmallows. Cook, stirring frequently, until the marshmallows have fully melted. Stir in the bourbon, if using, and the vanilla.

Step 4

Remove the pan from the heat and stir in the crushed chips and remaining about 1 cup marshmallows. Stir just until combined.

Step 5

Using a rubber spatula sprayed with a little nonstick cooking spray, scrape the mixture into the prepared baking pan and press it down into an even layer. Set aside to cool completely to room temperature before cutting into 16 equal squares.

Step 6

Store any leftovers in an airtight container for up to 5 days.