Combine the instant coffee, boiling water and butter, and stir until the coffee has dissolved and the butter has melted.

In another bowl combine the sweetener, coconut flour, baking powder salt, and hazelnut flour.

Add the coffee mixture to the dry ingredients, then add egg and stir until the mixture is completely combined.

Grease a coffee mug with butter or coconut oil. Add the cake batter into the coffee mug. (You will want to make sure the coffee mug is a similar size to your serving glass)

Place the coffee mug in the microwave and cook on high for 1 minute.

Allow the cake to rest for 1-2 minutes. Then remove the cake from the mug by tipping it upside down onto a plate.

Set the cake aside to cool completely.

Separate the egg white from the yolk and place it into 2 separate bowls.

Whisk the egg white until it forms stiff peaks.

In the other bowl, combine egg yolk, vanilla, sweetener, and salt and whisk until pale in color and thick in texture.

Add mascarpone to the egg yolk mixture and whisk to combine.

Add the whipped egg whites to the mixture and fold to combine. Be careful to not knock all the air out of the egg whites.

Cut the cake in half. You should end up with 2 evenly sized discs.

In your 2 serving glasses, place one-quarter of the mascarpone mixture into each glass

Place the cake discs into each glass on top of the mascarpone layer

Pour half a teaspoon of brandy evenly onto each cake.

Divide the remaining mascarpone filling evenly on top of each cake disc.

Using a tea strainer, lightly dust some cocoa powder on top of each tiramisu to serve.