To make the Citrus Mug Cake, combine butter, almond flour, baking powder, sweetener (or egg white), egg whites, lemon juice, and lemon zest in a mug. Mix well.
Microwave the mug on high for 1 minute or until the cake is cooked.
To make the Citrus Glaze, mix softened cream cheese, powdered sugar, thick cream, lemon juice, and lemon zest in a bowl until well combined.
Drizzle the Citrus Glaze over the cooked Citrus Mug Cake and enjoy!