Temper eggs and buttermilk: In a 3-quart saucepan, heat 1 to 2 inches of water over low heat to 150 °F / 66 °C. In a medium metal bowl, whisk eggs until homogenous. Add buttermilk and whisk until well combined. Set bowl in water bath and warm buttermilk mixture, whisking constantly, until it reaches body temperature, 20 to 40 seconds. Set bowl aside, and discard water bath.

Make batter: Sift flour, sugar, buttermilk powder (if using), baking powder, and salt through a fine-mesh strainer into a large bowl. Make a well in center of mixture. Add buttermilk mixture to flour mixture and whisk until well combined with some lumps remaining, about 20 seconds. Do not overmix. Whisk in melted butter until fully incorporated; batter should still have some small lumps. Set aside.

Cook pancakes: Heat a dry 10-inch cast iron skillet or griddle or nonstick skillet, over medium heat for 2 minutes. Add ½ teaspoon butter to pan and swirl until butter is fully melted and foaming. Using a paper towel, wipe out pan, leaving thin film of butter over entire surface of pan. Ladle batter into pan according to your pancake size preference. Cook, undisturbed, until bubbles that appear on top of pancake(s) begin to pop and bottom side is evenly browned, 2 to 3 minutes. Flip pancake(s) and continue to cook until second side is evenly browned and pancake(s) spring back when gently pressed with your finger, 1 to 2 minutes. Transfer pancake(s) to plate, or to a wire rack set inside a ½ sheet pan if you want to cook all the pancakes before serving. Repeat with remaining batter.

Top and serve: Divide pancakes between plates, top with butter and warm syrup (if using), and serve.