Whisk together flour, sugar and salt. In a separate bowl, whisk together milk, egg and melted butter. Slowly whisk the wet ingredients into the dry, mixing until there are no more bits of dry ingredients (lumps are okay).
Heat a griddle or large skillet over medium-low heat and grease with butter. Grease the ring molds with butter or cooking spray and place on the griddle. Add about 1/3 cup of batter to each ring mold and let the pancake cook, about 1 minute. Be sure that the batter is touching all the edges of the ring mold so that when you add the maple syrup, it won't leak out.
Add about 1 tbsp of maple syrup to the top of each pancake. Use a toothpick or a spoon to swirl the maple syrup into the batter.
Cook until the pancakes are beginning to bubble around the edges and the ring molds release easily, about 3-4 minutes. Then remove the ring molds (using an oven mitt, they will be hot) and use a spatula to flip the pancakes. Cook until browned on the second side, 2-3 minutes.
Set the pancakes aside on a sheet tray and repeat this process until you have 6 pancakes; these will be your sandwich buns. You may have extra batter, but it took me some trial and error to make 6 perfect buns, so you may need to use the extra batter. If not, you can simply cook them up as regular pancakes.