Heat an electric griddle to 375ºF or a skillet over medium-high heat.
In a large bowl, whisk together buckwheat flour, all-purpose flour, sugar, baking powder, baking soda, and salt. Set aside.
In a medium bowl, whisk together milk, eggs, and vanilla.
While whisking, pour the wet ingredients and the melted butter into the dry ingredients and whisk until just combined.
Place 1 teaspoon of butter or oil onto the preheated griddle; use a spatula to spread it around and coat the griddle. Scoop batter by about 1/4 cup portions onto the hot griddle. Cook the pancakes for 3-4 minutes or until bubbles form and do not disappear. Cook the pancakes on the second side for about 1 minute or until pancakes are cooked through.
Repeat with the rest of the pancake batter, adding more butter or oil to the griddle as needed.