Add graham cracker crumbs, flour, baking powder, and brown sugar to a large mixing bowl and whisk to combine. Set aside.
Combine the milk, egg, and 1 teaspoon of vanilla extract in a small bowl and beat with a fork or small whisk until just combined.
Pour the wet ingredients into the bowl with the dry ingredients and mix with a wire whisk until well combined.
Melt the butter fully in the microwave and add it to the batter. Beat with a whisk until smooth.
Add the chocolate chips to the bowl and stir to combine.
Preheat a large skillet on the stovetop over medium heat and grease the skillet with butter or oil.
Pour ¼ cup portions of batter onto the preheated skillet. Cook until tiny bubbles begin to form and pop, then flip and cook the other side until golden brown. Repeat the process until all the batter is used up.
Place the pancakes on a wire cooling rack to cool.
Add the heavy whipping cream, the remaining teaspoon of vanilla extract, and the powdered sugar to the bowl of a stand mixer and beat until stiff peaks form when the beater is lifted. This takes approximately 2 minutes.
Spoon the whipped cream into a large piping bag and pipe large dollops of whipped cream onto a stack of pancakes. Top with chocolate chips and marshmallow bits.
Serve the pancakes warm with a drizzle of pure maple syrup, if desired.