Cook the pancakes until the bubbles that rise to the surface stop closing up immediately upon popping, 2 to 4 minutes. (If using blueberries, add 4 to 6 blueberries to each pancake before flipping and let them sink into the batter.0
When a small crater appears and remains such, and the bottom of the pancake looks golden-brown, then you can flip (a fish spatula makes the flipping much easier). Cook until the other sides are lightly browned, about 1 to 2 minutes. Keep in mind that the longer you cook the pancakes, the slightly faster this process will go as the pan or griddle will be more thoroughly heated through; trust your eyes and nose more than the time frame. Remove pancakes to a wire rack set inside a rimmed baking sheet, and keep in the warmed oven until all the batter is used up and you are ready to eat. In between batches of pancakes, brush your cooking surface with more melted butter.