Sour cream thyme rolls

1/2 cup (1 stick) cold unsalted butter, cut into small pieces, plus 2 tablespoons melted, plus more for the muffin tin and plastic wrap
1 envelope ( 1/4 ounce) active dry yeast
1 cup warm water (105to 110F)
2 tablespoons sugar
2 cups cake flour (not self-rising)
2 cups all-purpose flour
1 1/2 teaspoons salt
11/2 cups sour cream
2 tablespoons fresh thyme leaves

Lightly butter a standard 12-cup muffin tin, and set aside. Stir together the yeast, warm water, and sugar in a small bowl, and let stand until foamy, about 5 minutes. Stir until the yeast dissolves.
Whisk together the flours and salt in a large bowl. Using a pastry blender, cut in the butter pieces until mixture resembles coarse meal. Stir in the yeast mixture. Stir in the sour cream and thyme leaves until combined.
Spoon heaping 1/3 cup dough into each cup of the muffin tin. Cover with buttered plastic wrap; let rise in a warm place until doubled in size, about 1 hour.
Preheat the oven to 400F. Bake the rolls 10 minutes. Remove from the oven, and lightly brush with 2 tablespoons melted butter. Bake until golden brown, 16 to 18 minutes. Immediately invert and unmold rolls onto a wire rack. Serve warm.

MAKES 12