Finely chop dark chocolate and place it in a bowl. Heat heavy cream in a saucepan until hot, pour it over the chocolate, let it sit, then stir until smooth and glossy. Set aside to thicken.

Sift together almond flour, powdered sugar, and cocoa powder into a mixing bowl to eliminate lumps.

In a stand mixer, whisk aged egg whites until frothy. Gradually add granulated sugar while whisking, then increase to high until stiff peaks form.

Gently fold the dry ingredients into the meringue in two additions until a smooth batter forms. Stop folding once it reaches a lava-like consistency.

Pipe 1-inch rounds of batter onto lined baking sheet, tap to release air bubbles, and let rest at room temperature for 30-45 minutes.

Preheat oven to 300°F (150°C) and bake macarons for 13-15 minutes until they hold their shape. Cool completely on the baking sheet.

Pair similar shells, fill with ganache, top with whipped Swiss meringue and mini marshmallows if desired. Store in the fridge for 12-24 hours before serving.