The secret to high-rise soufflé pancakes is all about speed and temperature: Cold egg whites whip more slowly than room temperature ones, but they form stronger, more uniform bubbles, and whipping them on medium speed incorporates more air. Finally, piping the batter in one swift pass allows you to create more height from the beginning without overcooking each pancake.
How to Make It
Whisk together flour, baking powder, and salt in a medium bowl. Whisk together 6 egg yolks, milk, and vanilla in a large bowl. Gradually sift flour mixture into yolk mixture; whisk until smooth. Chill at least 20 minutes or up to overnight (about 8 hours).
Place 8 egg whites in bowl of a heavy-duty stand mixer (save remaining yolks for another use). Freeze until egg whites are partially frozen, about 15 minutes. Add lemon juice to egg whites, and beat with a whisk attachment on medium speed, gradually adding sugar, until glossy and stiff peaks form, 6 to 8 minutes. Using a hand whisk, gently fold egg white mixture into chilled batter, in 2 additions, until just incorporated. Using a rubber spatula, finish folding, if needed, to fully incorporate. Transfer half of batter to a large piping bag or ziplock plastic bag with a 1-inch hole cut in one corner. Keep remaining batter chilled, uncovered, while cooking the first batch.
Preheat a large electric griddle to 300°F. Lightly grease griddle with butter. Pipe 4 cone-shaped mounds of batter, about 3 inches wide on bottom and 3 inches tall (do not layer the batter), leaving at least 2 inches between mounds. (Make sure pancakes are close enough so that all 4 mounds will fit under the aluminum pan.) Spoon 2 tablespoons water on surface of the griddle around the pancakes. Immediately cover pancakes with the inverted aluminum pan to steam-griddle them. Cook until top of batter looks dry and bottom of pancakes are lightly browned, 5 to 6 minutes. Using 2 thin spatulas (such as fish spatulas), carefully flip pancakes. Spoon 2 tablespoons water on surface of griddle around pancakes. Cover with inverted aluminum pan, and cook until pancakes are set, 5 to 6 minutes. Transfer pancakes to serving plates. Repeat process with remaining batter and water. Top with butter and maple syrup. Sprinkle with powdered sugar. Serve immediately.
Notes
To make one giant soufflé pancake: Grease a 3-quart multicooker insert with softened butter. Fill with half the batch of batter, and smooth top. Cover and cook on Cake function until top is set, about 35 minutes. Use a small offset spatula to loosen sides of pancake. Invert onto a serving platter.