Melt butter in a ramekin and brush all sides to ensure it is well greased.
Add almond flour, baking powder, and salt and mix well. Whisk in the egg white.
Microwave for 90 seconds. Let cool for 30 seconds before removing.
Notes
TO STORE. Leftover English muffins can be stored in an airtight container at room temperature for up to 3 days or in the fridge for up to 1 week. TO FREEZE. Store leftover muffins in a freezer-safe container and freeze for up to 3 months. Allow the muffins to thaw overnight in the fridge before slicing and toasting them.