Jam and Cream Cheese Texas Kolaches

Name: Jam and Cream Cheese Texas Kolaches
Ingredients: 2 1/4 cups all-purpose flour, divided; 4 tablespoons plus 1/2 teaspoon granulated sugar, divided; 1 (1/4-ounce) packet dry active yeast (2 1/2 teaspoons); 1/2 cup plus 1 tablespoon whole or 2% milk, divided; 6 tablespoons unsalted butter, plus more for greasing; 2 teaspoons vanilla extract, divided; 3/4 teaspoon kosher salt; 2 large eggs; 1 medium lemon; 3 tablespoons apricot, strawberry, peach, or blueberry jam; 4 ounces cream cheese; 1/4 cup sour cream; Poppy seeds, for sprinkling