1 Separate the eggs. Place yolks in a mixing bowl and whites in a tall vessel. Use a hand mixer to beat the egg whites with 1/2 tablespoon sugar and the salt until stiff and refrigerate.
2 Meanwhile, rinse the blueberries in a bowl of water, then drain and gently pat dry.
3 Add remaining sugar, milk, flour and oats to yolks and stir to combine. Let the batter rest for 10-15 minutes.
4 Fold beaten egg whites into the batter with a spatula.
5 Heat 1 teaspoon oil in a large non-stick pan. Pour in batter, sprinkle with 2/3 of the blueberries and cook pancake over medium heat until the bottom has set, about 4 minutes.
6 Flip pancake, pour remaining oil into pan (lift pancake to allow oil to flow underneath) and continue to cook for 1-2 minutes.
7 Cut pancake with 2 spatulas into pieces. Add butter and continue to cook for 1-2 minutes, shaking pan slightly to prevent pancake from scorching. Serve with remaining blueberries and sprinkled with powdered sugar.