Combine milk, water, yeast, sugar, flour, melted butter, and salt in a stand mixer. Knead for 6-8 minutes until smooth. Let rise for 15 minutes.

In a saucepan, combine cocoa powder, cream, chocolate chips, and sugar. Stir until smooth, then mix in melted butter, vanilla, and salt. Cool and stir in graham cracker crumbs.

Roll dough into a rectangle, brush with butter, spread filling, sprinkle crumbs, roll tightly, and slice into 12 pieces. Place in a greased baking pan.

Preheat oven to 350°F (175°C). Let rolls rest for 10 minutes, then bake for 25-28 minutes until golden brown. Cool for 5 minutes before adding meringue.

In a double boiler, whisk egg whites and sugar until warm. Beat until stiff peaks form. Add cream of tartar and vanilla, and mix until incorporated.

Spread meringue over rolls and toast with a torch until golden brown, about 1-3 minutes. Let sit for a few minutes before serving.