In a stand mixer, combine milk, lukewarm water, instant yeast, granulated sugar, all-purpose flour, melted unsalted butter, and salt. Mix on low speed until the ingredients start to come together, then increase to medium and knead for 6-8 minutes until the dough is smooth and elastic.

Cover the bowl with a damp cloth and let the dough rest for 15 minutes in a warm area.

In a saucepan, combine unsweetened cocoa powder, heavy whipping cream, semi-sweet chocolate chips, granulated sugar, butter, vanilla extract, and a pinch of salt. Heat over low to medium heat, whisking continuously until the chocolate and cream blend into a smooth, glossy filling.

Allow the mixture to cool slightly before gently folding in the graham cracker crumbs for added texture.

Once the dough has rested, transfer it onto a lightly floured surface. Roll it out into a rectangle about ¼-inch thick. Brush melted butter generously over the dough, then evenly spread the cooled chocolate filling on top, followed by a sprinkle of graham cracker crumbs.

Starting at one edge, tightly roll the dough into a log shape, ensuring the filling stays inside. Pinch the seams to seal, then use a sharp knife to cut the roll into 1½-inch segments.

Place these cut rolls, cut side up, in a greased baking dish, leaving some space between each. Cover loosely with a cloth and let them rise for about 20 minutes.

Preheat your oven to 350°F (175°C). Bake the S'mores Rolls for 25-28 minutes until they are beautifully golden brown and puffed.

Once done, remove them from the oven and allow them to cool slightly in the pan before adding the meringue topping.

In a bain-marie setup, combine egg whites and granulated sugar, whisking continuously until the sugar has completely dissolved and the mixture is warm to the touch.

Transfer this mixture to a stand mixer and beat on high speed until stiff peaks form. Add cream of tartar and vanilla extract in the final stages for extra stability and flavor.

Once your S'mores Rolls have cooled for a bit, generously dollop the meringue over each roll, spreading it to the edges.

For a lightly toasted finish, place the rolls under the broiler for 1-2 minutes, watching closely to avoid burning, or use a kitchen torch for a more controlled caramelization.