Roasted Sweet Potato and Fontina Pierogi

Name: Roasted Sweet Potato and Fontina Pierogi
Prep time: 30 min
Cook time: 45 min
Total time: 1 h 15 min
Cuisine: American
Ingredients: 2 large sweet potatoes, (peeled and cubes); 1 tablespoon olive oil; ½ teaspoon salt; ½ teaspoon freshly cracked pepper; ½ teaspoon garlic powder; 1 ½ cups fontina cheese, (freshly grated); 2 1/4 cups all-purpose flour; 1 teaspoon salt; 1 tablespoons unsalted butter, (melted); 1 cup plain greek yogurt or sour cream; 1 large egg; 1 large egg yolk; 1 tablespoon canola or vegetable oil; 3 to 4 tablespoons unsalted butter, (for browning/crisping the pierogi); plain greek yogurt, (or sour cream for serving); freshly chopped chives