In a medium saucepan, melt the butter over medium heat. Keep cooking the butter, stirring frequently. It will start to foam, and after about 5-7 minutes, you’ll notice brown specks forming at the bottom of the pan. The butter will also take on a nutty aroma—this means it's browned!

Once the butter has browned, remove it from the heat immediately to avoid burning. Let it cool for a few minutes before using it in your blondie batter.

In a large mixing bowl, whisk together the browned butter and both sugars until smooth.

Add the egg, egg yolks, and vanilla extract, mixing until fully combined.

In another bowl, whisk together the flour, baking powder, and salt. Gradually fold the dry ingredients into the wet ingredients until everything is well combined.

Grab your graham crackers and line the bottom of the pan with a single layer. You want full coverage, so break the crackers as needed to make sure they fit snugly.

Once that’s ready, spread half of the blondie batter evenly over the graham cracker layer. Use a spatula to smooth it out, making sure to get into all the corners.

Next, grab your last 4 graham crackers and add another layer on top of the blondie batter. Push them down just a bit so they’re firmly in place.

Pour the remaining blondie batter over the top graham cracker layer, spreading it out as evenly as possible. Don’t stress too much if a few graham bits peek through.

Pop the whole thing into your preheated oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out mostly clean (a few moist crumbs are fine). Let the bars cool completely in the pan. Resist the urge to cut in too soon!

Once the blondies are cooled, it's time to start your ganache. In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Pour the hot cream over your chocolate chips or chunks and let it sit for a few minutes. After a little wait, stir the mixture until it’s smooth and glossy.

Pour the ganache over the cooled blondie base and spread it out with a spatula to cover the top. Pop the pan in the fridge and let the ganache set for about 30 minutes.

While the ganache is setting, whisk together the egg whites and granulated sugar in a heatproof bowl over a saucepan of simmering water (double boiler style). Keep whisking until the sugar dissolves and the mixture is warm.

Transfer the egg white mixture to a stand mixer (or use a hand mixer) and whip on high speed until stiff peaks form, about 5-7 minutes. Add a splash of vanilla and mix until combined.

Once the ganache has set, spread the marshmallow fluff evenly over the top of the bars, creating a thick, fluffy layer.

Grab your pastry torch and carefully toast the marshmallow fluff until golden brown.

Let the bars cool again for a bit before slicing and serving. Enjoy the gooey s’mores goodness!