In a heat-proof bowl, combine chocolate, coffee, praline paste, and vanilla sugar.

In a medium-sized saucepan, heat milk until just before it begins to boil.

Pour milk into the bowl and blend with an immersion blender until all ingredients are fully dissolved and incorporated.

Preheat oven to 450 degrees Fahrenheit. Line a baking sheet with parchment paper.

Place marshmallows on baking sheet and bake for three to five minutes, until marshmallows begin to puff up and turn golden.

Using a soup ladle, spoon the hot mochaccino into glass mugs and top with roasted marshmallows.