Melt the butter in a large mug or ramekin in the microwave, about 30 seconds. Swirl the melted butter to coat the mug.
Add the almond milk, egg, almond flour, 2 tablespoons Swerve Confectioners, baking powder, salt, and extracts. Mix well. Gently place the blueberries on top of the batter (some will sink, that’s fine) and sprinkle on the sliced almonds.
Microwave on high power for 2½ - 3 minutes or until puffed and set. Let cool slightly and dust with additional Swerve Confectioners if desired.