In a saucepan, whisk together the unsweetened cocoa powder and water until smooth. Stir in the granulated sugar and salt, then place the pan over medium heat. Bring the mixture to a boil and let it continue boiling for 3 minutes, stirring occasionally. Remove from the heat and allow the sauce to cool; it will thicken slightly as it cools.

In a large bowl, combine the plain flour, finely crushed graham cracker crumbs, granulated sugar, baking powder, and salt. In a separate bowl, whisk together the milk, egg yolks, and vegetable oil. Pour the wet ingredients into the bowl of dry ingredients and mix just until combined; avoid overmixing to keep the pancakes fluffy.

In a clean bowl, use a hand mixer to beat the egg whites from the separated eggs until stiff peaks form. Gently fold the beaten egg whites into the pancake batter from Step 2 until just incorporated. This step makes the pancakes extra light—I never skip it for the fluffiest texture.

Heat a lightly oiled or buttered griddle over medium heat. Pour about 1/4 cup of pancake batter (from Step 3) onto the griddle for each pancake. Cook until bubbles form on the surface and the underside is golden brown. Flip and cook for another 1-2 minutes until browned on the other side. Repeat until all the batter is used.

In a small bowl, stir the hot water into the marshmallow creme, adding about 1 teaspoon at a time. Continue mixing until the sauce is smooth and pourable. I like to warm the water just a bit to make combining easier and ensure the sauce comes out silky.

Stack a few cooked pancakes from Step 4 onto each serving plate. Drizzle generously with the cooled chocolate sauce from Step 1 and the marshmallow sauce from Step 5. Serve immediately for the best melt-in-your-mouth S'mores pancake experience!