Ingredients

• 1 cup sour cream , at room temperature
• 2 teaspoons white sugar
• 1 , .25 ounce
• 1 egg
• 1 tablespoon white vinegar
• 1 tablespoon vegetable oil
• 3 cups all-purpose flour
• 0.5 cups unsalted butter

Instructions

1. 1 Combine 1 cup sour cream, 2 teaspoons sugar, and yeast in a bowl; let stand for 5 minutes. Stir in egg, vinegar, and oil.
2. 2 Add 3 cups flour to a large bowl. Cut in 1/2 cup butter with 2 knives or pastry blender until mixture resembles coarse crumbs. Stir in sour cream mixture until dough comes together.
3. 3 Turn dough out onto a floured surface; knead until smooth but still slightly tacky, about 10 minutes. Cut dough into 4 pieces; wrap each in plastic wrap. Refrigerate until firm, 2 hours or up to overnight.
4. 4 Preheat the oven to 350 degrees F (175 degrees C).
5. 5 Combine 2 1/2 cups sugar, 1 pound melted butter, and vanilla extract in a very large bowl; stir in 4 cups flour. Beat egg whites into filling mixture.
6. 6 Roll 1 piece dough on a lightly floured work surface into an 8x12-inch rectangle. Crumble 1/4 filling mixture on top, leaving a 1/2-inch border on long sides. Cover filling with plastic wrap; flatten with a rolling pin. Roll dough into a tight roll, starting with one of the long sides.
7. 7 Cut roll into 2-inch pieces at a slight angle. Arrange pieces on a rimmed baking sheet. Push tops down gently to flatten slightly. Repeat with remaining 3 dough pieces and filling.
8. 8 Whisk egg yolks and yogurt together; brush over dough pieces.
9. 9 Bake in the preheated oven until golden brown, 20 to 30 minutes. Cool before serving, about 15 minutes.

Nutrition per serving