Place pancake mix, milk, eggs, vanilla, and melted butter in blender and process until smooth. If possible, let mixture rest for at least 30 minutes. Alternatively, you can make the batter the day before and keep it in fridge overnight.
Place a 7- or 8-inch nonstick skillet (or crepe pan) over medium heat. Coat with a little bit of butter. Pour about ¼ cup batter in pan and gently tilt and swirl pan until batter evenly coats the bottom. If you're using a 7-inch pan, you may want to use slightly less than ¼ cup batter.
Let cook for about 1-1 ½ minutes until crepe is turning golden on bottom and edges are pulling away from pan. You can either use your fingers or a spatula to pull edges up and when ready, flip. Cook for another minute before removing crepe from pan to a plate.
Continue with remaining batter, adding a little butter to pan in between each.
Enjoy crepes with a little bit of maple syrup or add ham and cheese or the filling of your choice.