S'more Squares Please

Step 1 -Arrange the oven racks in the upper and lower thirds of the oven.

Step 2 -Preheat the oven to 350 degrees F.

Step 3 -Coat the inside of a 9x13-inch pan with nonstick spray and line it with parchment paper. Make sure to leave about 2 inches of parchment paper overhanging on the long sides of the pan.

Step 4 -In a food processor, add the whole graham crackers and pulse until it forms fine crumbs. Alternatively, you can place the graham crackers in a resealable plastic bag and then crush them using a rolling pin.

Step 5 -In the food processor, add the graham cracker crumbs, the flour, the baking powder, and the sea salt and pulse a few times to combine.

Step 6 -In the bowl of a stand mixer fitted with the paddle attachment, add the butter, the dark brown sugar, the granulated sugar and beat on medium speed until light and fluffy, about 4-5 minutes.

Step 7 -Add the eggs, 1 at a time, and mix well on medium speed, scraping the sides of the bowl after each addition.

Step 8 -Add the vanilla to the egg mixture and mix to combine.

Step 9 -Turn the mixer to low.

Step 10 -Add the graham cracker crumb mixture and mix until just combined.

Step 11 -Add about 3/4 of the chocolate to the dough and mix gently to incorporate.

Step 12 -Transfer the dough to the prepared pan.

Step 13 -Using damp hands, press the dough into an even layer.

Step 14 -Bake on the lower oven rack until the bars are golden at the edges and the surface has a crackly appearance, about 30-32 minutes.

Step 15 -Transfer the pan from the oven and evenly sprinkle the blondies with the marshmallows.

Step 16 -Bake on the top oven rack until the marshmallows have softened and begin to turn golden-brown, about 6-8 minutes.

Step 17 -Transfer the pan from the oven and puncture any puffed marshmallows with a toothpick.

Step 18 -Sprinkle the remaining chocolate over the marshmallow layer.

Step 19 -Bake on the top rack of the oven until the chocolate is melted and gooey and the marshmallows are lightly toasted, about 2 minutes.

Step 20 -Transfer the pan to a wire rack and let cool, about 45 minutes.

Step 21 -Run a knife on the short sides of the pan.

Step 22 -Using the parchment paper overhang, transfer the blondies from the pan.

Step 23 -Let the blondies cool for 10 minutes.

Step 24 -Slice and serve.