Directions

1. Whisk together warm water, sugar, and yeast in a medium bowl; let stand until foamy, about 5 minutes. Place salt and 3 cups of the flour in bowl of a stand mixer fitted with a paddle attachment. Add yeast mixture and melted butter, beating on low speed just until combined, about 30 seconds. Turn off mixer; switch to a dough hook attachment. Beat at medium-low speed until dough is smooth and elastic, 7 to 12 minutes, adding remaining 1/2 cup flour, 1/2 to 1 teaspoon at a time, as needed if dough is too sticky or not yet elastic. Coat a large bowl with cooking spray. Place dough in prepared bowl, turning to grease top. Cover and let rise in a warm place (75ºF), free from drafts, until dough is doubled in size, 1 hour to 1 hour, 15 minutes.
2. Combine garlic and 10 tablespoons of the butter in a medium saucepan. Cook over medium, stirring often, until butter is melted and garlic is aromatic, 2 to 3 minutes. Stir in kale, 1 tablespoon of the mustard, and 1/4 teaspoon of the salt. Remove from heat, and set aside.
3. Gently punch down dough. Divide dough equally into 22 pieces (about 1 ounce each); roll each into a tight ball. Dip each ball into butter-kale mixture, rolling to coat; arrange seam side down in a 10-inch cast-iron skillet coated with cooking spray. Sprinkle top evenly with cheese. Drizzle any remaining butter-kale mixture over rolls, arranging kale as desired. Cover with plastic wrap, and let rise in a warm place (75ºF), free from drafts, until almost doubled in size, 35 to 45 minutes. Meanwhile, preheat oven to 350°F.
4. Remove plastic wrap from skillet; place skillet on a rimmed baking sheet. Bake in preheated oven until rolls are browned and cooked through, about 30 minutes, loosely covering with aluminum foil during last 5 minutes of baking time, if needed. Transfer skillet to a wire rack, and let cool for 10 minutes.