Prep and heat the pan: Lightly grease three 3-inch pancake rings and set them on a wide, heavy skillet over very low heat. Have your yolk and white mixtures ready.

Whip the whites: In a clean, fat-free bowl, beat the egg whites with cream of tartar until stiff, glossy peaks form. Gradually add 2 tablespoons of sugar while beating. Do not overbeat—you want the whites to stay airy and smooth.

Make the yolk batter: In a separate bowl, whisk the yolks with milk and vanilla until smooth and pale. Sift in the cake flour and baking powder, whisking just until incorporated with no dry pockets.

Fold gently: Stir a small scoop of the whipped whites into the yolk batter to loosen it, then fold in the remaining whites in two additions. Use a light touch—fold, don’t stir—until the batter is thick, airy, and full of ribbons.

Cook and steam: Spoon batter into each ring to about 2/3 full. Smooth the tops with the back of a spoon. Cover the skillet and cook on low heat for 6–8 minutes, until the edges set and the centers look puffed and cloudlike.

Finish and serve: Carefully remove the rings, then flip the pancakes if you can do so without deflating them. Cook another 1–2 minutes to set the bottoms, then transfer to a plate. Serve with butter, maple syrup, and berries for the classic soufflé pancake finish.