This is a fast and tasty mug muffin recipe that can easily be used for a sandwich. You will need nut flour, coconut flour, ghee or butter, an egg, salt, baking soda, and lemon juice.
For baking powder, use 1/8 tsp baking soda and 1/4 tsp vinegar or lemon juice. I used distilled vinegar and didnb t taste it.
Original recipe located here: 2-Minute Low Carb English Muffin (Paleo, Gluten-Free)