Heat milk in a small saucepan over medium heat until lukewarm. Transfer milk to a large bowl, and stir in the sugar and yeast. Let stand until creamy, about 5 minutes.
Whisk in the flour, salt, butter, and egg yolks until batter is smooth. Cover bowl tightly with plastic wrap. Transfer bowl to a warm place; let dough rise until doubled (about 1 1/2 hours).
Heat griddle to 375 degrees F and oven to 175 degrees F.
Using a 2-ounce (1/4-cup) ladle, pour batter onto griddle, creating several pools 2 inches apart. Cook pancakes until bubbles form on the top and the edges are slightly dry, about 3 minutes. Using a spatula, flip the pancakes; cook until golden on bottom, about 1 1/2 minutes. Transfer to a heatproof plate; keep in warm oven. Repeat with the remaining batter. Serve warm.
(c)2003 Martha Stewart Living Omnimedia, Inc. All Rights Reserved.