Preheat your oven to 325°F (163°C). Line an 8×8 inch pan with parchment paper.

In a bowl, mix the melted butter with sugar, eggs, vanilla, salt, and cocoa powder until glossy. Gently stir in the flour and spread it in the pan. Bake for 20–22 minutes or until a toothpick comes out clean.

Beat the softened cream cheese until smooth. Gradually mix in the sugar, sour cream, melted chocolate, vanilla, espresso powder, and salt. Add eggs one at a time, beating well. Pour over the cooled brownie base.

Bake at 325°F for 35–40 minutes until center is set. Cool for 1 hour at room temperature, then refrigerate for at least 4 hours.

Whisk egg whites and sugar over a double boiler until warm and sugar is dissolved. Remove from heat and whip until stiff peaks form. Spread the meringue on the cheesecake.

Toast the meringue gently with a kitchen torch or broiler for 30–60 seconds. Optionally, sprinkle mini marshmallows on top.