For the Graham Cracker Crust

1. Preheat your oven to 350 degrees Fahrenheit. Line a 12-cavity muffin tin with liners.
2. In a medium bowl, use a fork to combine fine graham cracker crumbs, melted butter, and granulated sugar together. Mix for about 2 minutes to ensure the butter has fully distributed into the crumbs.
3. Evenly divide the crumbs between each cavity, about 1 1/2 tablespoons of the mixture in each muffin liner.
4. Bake the crusts for about 3-5 minutes until lightly golden brown to keep the crusts from breaking apart.

For the Brownie Cupcakes

1. Place a medium, heat-proof bowl on top of a saucepan filled about halfway with water. When the bowl is placed on top of the saucepan, the water should not touch the bottom of a bowl.
2. Place your chocolate chips and chopped butter in the heat proof bowl and stir over medium-high heat until smooth and fully melted. Allow the mixture to cool for about 5 minutes as you are preparing the
3. In a large bowl or in the bowl of your stand mixer fitted with a whisk attachment, beat your room temperature eggs, light brown sugar, and granulated sugar on medium-high speed for 2-3 minutes. The mixture should be lighter in color, slightly greater in volume, and fluffier in texture.
4. Add melted chocolate and butter mixture to the egg mixture and stir until combined.
5. Carefully, stir or whisk all purpose flour, baking powder, and salt into your wet ingredients only until the dry ingredients disappear into the wet. Do not mix past this, as doing so could lead to drier, cakier brownies.
6. Divide the batter evenly into the cavities. The batter should almost reach the top of each liner.
7. Bake for about 25 minutes or until a toothpick inserted into the center of the brownie cupcake comes out with moist batter. It should not look slimy, but it should look like gooey crumbs rather than dry crumbs or a clean toothpick. Allow the brownies to fully cool before frosting.

For the Frosting 

1. In a large bowl with a hand mixer or in the bowl of your stand mixer fitted with a paddle attachment, beat your butter on high speed until smooth, about 1 minute.
2. Slowly, add powdered sugar to the butter on low speed to avoid a big mess. Beat marshmallow fluff into the mixture on high speed.
3. Add heavy whipping cream to the frosting, and beat on high speed for 2-3 minutes. This creates a lighter, more velvety frosting texture.

For the Decoration

1. Transfer your frosting to a piping bag fitted with a tip of your choice or towards one side of a Ziploc bag if desired. You can also use a spoon and knife to spread your frosting onto the cupcakes.
2. Frost cupcakes as desired and sprinkle with remaining graham cracker crumbs.
3. Top each cupcake with a Hershey square.
4. Store covered and at room temperature for up to 5 days. Brownies will lose moisture the longer they sit.