Step 1

Preheat oven to 350°. Spray two 8x8-inch pans with cooking spray and line with parchment paper.

Step 2

In a medium bowl, stir brownie mix, egg, oil and water until well blended.

Step 3

Transfer half of the batter to each of the prepared pans and spread evenly.

Step 4

Bake the brownies for 18 minutes.

Step 5

Remove the brownies from the oven and allow to cool for 5 minutes.

Step 6

Add 2 cups of marshmallows to the top of one pan of brownies, followed by a layer of graham crackers.

Step 7

Add remaining 2 cups marshmallows on top of the graham crackers. Flip the other brownie onto the layers and gently press.

Step 8

Remove the parchment from the bottom of the brownie. Cover pan with foil and bake for an additional 10 minutes.

Step 9

Allow to cool for 5 minutes, then gently press down on the layers to help the layer stick together.

Step 10

Carefully remove brownie from the pan and remove the other layer of parchment.

Step 11

Cut in 18 mini bars.

Step 12

Tip: When cutting the bars, spray your knife with cooking spray to help prevent the marshmallows from sticking.