Heat oven to 350°F. Line bottoms of 14-inch, 9-inch and 6-inch round cake pans with waxed or parchment paper.

Resift flour with baking powder twice; set aside.

Heat milk with butter in small saucepan over medium heat until butter is melted. Reduce heat to low and keep hot; do not simmer.

Combine sugar, eggs and yolks in 5-quart bowl of electric mixer. Set bowl over pan of hot water over low heat; do not let water boil.

Whisk until sugar is dissolved and mixture is warm to touch.

Transfer bowl to mixer and beat at high speed using whisk attachment until cool, tripled in volume and consistency of thick whipped cream.

Transfer batter to larger bowl. Sift ⅓ of flour mixture over batter and fold in gently using rubber spatula.

Fold remaining flour into batter in 2 more batches.

Pour hot milk mixture into batter in 3 batches, continuing to fold gently until all milk mixture is completely incorporated.

Pour batter to equal depth in prepared pans.

Bake until cakes are browned and spring back when lightly pressed, about 17 to 20 minutes for 6-inch, 20 to 25 minutes for 9-inch and 25 to 30 minutes for 14-inch.

Cool completely in pans on racks.

Invert cakes onto respective 14-inch, 9-inch and 6-inch fiberboard discs.

Carefully peel off parchment liners.

Cover tightly with plastic wrap. Refrigerate if made more than 1 day ahead; otherwise store cakes at room temperature.