In a non-stick skillet over medium heat, melt a little butter. Pour ¼ cup (60 ml) of batter and spread it, tilting the skillet to obtain a 6-inch (15 cm) pancake. If using frozen and thawed blueberries, scatter 1 tbsp of blueberries over each pancake. Cook for 2 minutes on each side. Stack them in a warm oven as you go.