Take your cream cheese out of the fridge to soften. Choose a large, microwave-safe mug (at least 12 oz / 350ml capacity). Ensure all ingredients are measured and ready.

In a small mixing bowl, combine the room-temperature egg and 35g of sugar. Use a hand whisk or electric mixer to beat them together vigorously for 2-3 minutes until the mixture becomes pale yellow, thick, and forms ribbons that slowly disappear when you lift the whisk.

Sift the 55g of cake flour and 25g of cocoa powder directly into the egg mixture.

Use a spatula to gently fold the dry ingredients in until just combined and no dry pockets remain. Be careful not to overmix.

Melt the butter and dark chocolate together over a hot-water bath, cool slightly, then pour into the batter and fold to combine.

Pour the brownie batter into your mug or baking vessel and smooth the top.

Bake at 180°C for 20 minutes, or microwave in short intervals until set in the center.

Place on a cooling rack and let it cool completely to room temperature (about 30 minutes).

While the brownie cools, make the frosting.

In a small bowl, combine the softened 180g of cream cheese and 15g of sugar.

Stir vigorously with a spatula or spoon until the mixture is completely smooth, creamy, and free of any lumps. Set aside.

Place the 45g of dark chocolate in a clean microwave-safe bowl. Melt it using the same 20-second burst method, stirring until smooth. Let it cool for 2-3 minutes until it is no longer hot to the touch but still liquid.

Once the brownie base is completely cool, spread the cream cheese frosting evenly over the top with a spoon or small spatula.

Carefully pour the cooled, melted chocolate over the cream cheese layer. Gently tilt and rotate the mug to encourage the chocolate to flow and cover the entire surface in a thin, even layer.

Place the mug in the refrigerator for at least 30 minutes to allow the chocolate crust to harden completely. Once set, the top will be firm and glossy. Enjoy directly from the mug with a spoon!