Nut-filled Butterhorns - Red Star® Yeast

Ingredients

• 4 cups all-purpose flour, divided
• 1 tablespoon granulated sugar
• 1 teaspoon table salt
• 2 (0.25oz each) packages (14g) or 4 1/2 teaspoons Red Star Active Dry Yeast
• 1/4 cup water
• 1/2 cup sour cream
• 1 cup butter (room temperature)
• 4 large egg yolks
• 4 large egg whites
• 1 cup granulated sugar
• 1 teaspoon vanilla
• 1 cup walnuts (finely chopped)
• Confectioners' sugar for dusting