Step 1Melt the butter in the microwave in a 4-quart bowl. Add the egg, buttermilk and sugar and whisk until well mixed. Add the flour, baking soda and salt. Whisk well. Stir in the sour cream. (This can be mixed a day ahead and refrigerated. Stir well before using.)
Step 2Lightly butter a nonstick griddle set over medium-high heat. When hot, spoon about 2 tablespoons of batter for each pancake onto the griddle. Scatter 4 to 5 blueberries on each. When the batter is set and the undersides are brown, about 2 minutes, flip, then brown the other sides. The pancakes can be kept warm in a 200-degree oven while the remaining pancakes are cooking.
Step 3Serve hot with warm maple syrup.