Remove the fermented batter from the refrigerator. Add the baking powder, baking soda, salt, eggs, melted butter, vanilla extract, and remaining milk.
Whisk until the ingredients are thoroughly incorporated. A few small lumps are fine. It's going to be **thick** and that's lovely.
Let the batter rest at room temperature for approximately 20 minutes. Meanwhile, preheat a griddle or large skillet over medium to medium-low heat.
Melt a small amount of butter on the hot griddle. Pour the desired amount of batter onto the griddle and gently spread it if necessary. I use almost a full cup for big, fluffy pancakes. You can use less batter for smaller pancakes.
Cook until bubbles form across the surface and the edges begin to look set. Flip and cook the opposite side until golden brown and cooked through.
Repeat with the remaining batter, adding more butter to the griddle between batches as needed.
Serve warm with maple syrup and cinnamon-maple whipped butter, if desired.