To a mug or ramekin, add the almond flour. Pour the melted butter on top and mix to combine. Using the back of the measuring spoon press the crust into the bottom of the cup and slightly up the sides.
Cook the crust 25 seconds in the microwave) (based on a 1200 watt microwave); set aside.
Place the egg and salt in a small bowl; whisk to combine; set aside.
Mix in the sugar.
Pour mixture over the crust. Microwave for 50 seconds.
Remove and set aside to cool until set. Refrigeration will speed up this process.
*If you use a shallow ramekin made for creme brulee, use 3 tablespoons almond flour + 1 tablespoon butter.
**For egg-free, substitute the 1 tablespoon of beaten egg with 2 teaspoons liquid from a can of cannellini beans plus 1 teaspoon additional butter or margarine.