Ingredients

• 1 1/4-ounce envelope active dry yeast
• 1/2 cup plus 2 1/3 cups all-purpose flour
• 2 teaspoons plus 3 tablespoons sugar
• 2 large eggs, separated
• 2 1/2 cups half-and-half, room temperature
• 1/4 cup (1/2 stick) unsalted butter, melted, plus more, chilled, for skillet
• 2 teaspoons kosher salt

Instructions

1. Mix yeast, 1/2 cup flour, 2 teaspoons sugar, and 1 cup water in a large bowl. Cover and let sit in a warm place until entire surface is foamy and puffed in places, about 30 minutes. If this doesn't happen, your yeast is past its prime; start again with a fresh package.
2. Add egg yolks, half-and-half, melted butter, salt, remaining 2 1/3 cups flour, and remaining 3 tablespoons sugar to mixture and whisk until smooth. Cover batter and let sit in a warm place until almost tripled in volume, 3-4 hours. (Or, to make ahead, cover and chill 8-12 hours. Bring to room temperature before proceeding.)
3. Whisk egg whites in a medium bowl to soft peaks; fold into batter. Melt about 1/2 tablespoons butter in a large nonstick skillet over medium heat. Scoop in heaping tablespoonfuls of batter to make 2" blinis. Cook until bubbles form on top and bottoms are golden brown, about 3 minutes. Flip and cook until other sides are golden brown, about 3 minutes. Transfer blinis to wire racks. Repeat with remaining batter, wiping out skillet and adding more butter as needed.