Step 1: In a large bowl, whisk together the 1 1/2 cups all-purpose flour, granulated sugar, baking powder, baking soda, and salt until well combined and lump-free.
Step 2: In a separate medium bowl, whisk together the buttermilk, large eggs, and melted unsalted butter until smooth.
Step 3: Pour the wet ingredients into the dry ingredients. Stir gently with a whisk or spatula until just combined. The batter should still have some lumps; do not overmix.
Step 4: If desired, toss the fresh or frozen blueberries with 1 tablespoon of flour to prevent them from sinking. Gently fold the blueberries into the pancake batter.
Step 5: Heat a lightly oiled griddle or large non-stick pan over medium heat. A few drops of water should sizzle and evaporate quickly when dropped onto the surface.
Step 6: Pour approximately 1/4 cup of batter per pancake onto the hot griddle, leaving some space between each pancake.
Step 7: Cook for 2-3 minutes, or until bubbles begin to form on the surface and the edges look set. Gently flip the pancakes and cook for another 1-2 minutes, or until golden brown and cooked through.
Step 8: Transfer cooked pancakes to a plate and serve immediately with your favorite toppings. To keep subsequent batches warm, you can place them on a baking sheet in a preheated oven at 200°F (95°C).