Add the muffin mix into a bowl. Pour the milk and add the egg to the bowl. Use a fork to break up the egg first, and then mix with a whisk or fork until the batter is smooth. Wait 5 minutes for the batter to set.
Cook the pancakes:
Heat a non-stick griddle or large pan over medium-high heat. Once hot, grease, spray, or melt butter on the hot surface. When using an electric griddle, heat it somewhere between 300 and 350F.
Immediately, pour ¼ cup of pancake batter onto the greased pan. Cook the pancakes for about 2 minutes, until the edges look defined and bubbles form. Flip the pancakes over and cook for another minute on the other side. Remove from the pan onto a plate and cook the remaining pancakes.
Serve:
Serve the pancakes warm, topped with your favorite toppings.
Notes
If you have a large box of muffin mix (usually about 16 oz) that yields 12 regular muffins, you'll need to measure half of the mix or 1 ⅓ cups to make 6 pancakes. Or, use the whole box + 1 cup milk + 1 egg to make 12 pancakes.