In a large bowl, whisk together the buckwheat flour (or mixture of buckwheat and whole wheat flour), baking powder, baking soda, sugar, and salt.
Add the egg, buttermilk, and vanilla. Stir until combined, but don’t overmix! Let the batter stand for 10 minutes.
Next, fold in 2 tablespoons melted butter until just combined. Let stand for another 10 minutes. The batter should thicken slightly as the dry ingredients absorb liquid.
Heat your griddle or cast iron skillet over medium heat. Add butter to coat the pan. When the butter sizzles, but doesn’t turn brown too fast, the heat is correct. Pour ⅓ cup of batter for each pancake (you can also make them larger or smaller as you prefer). Cook until the bottom is browned and bubbles form on the top of each pancake (about 2 to 2½ minutes). Flip the pancake once. Cook until it springs back when pressed in the center (about 2 minutes). Transfer to a serving plate. Repeat with the remaining batter.
Serve buckwheat pancakes warm, topped with butter, maple syrup, and maybe a little fresh fruit on the side!