Easy Shepherd’s Pie

Easy Shepherd’s Pie, a rich, savory casserole of ground meat and vegetables baked with mashed potatoes on top, was one of my favorite dinners as a kid (mostly for the potatoes). Today I love it even more for the hearty filling—and the quick prep time!

• 1 1/2 pounds russet potatoes
• 3 tablespoons unsalted butter diced
• 1/4 cup freshly grated Parmesan cheese
• 1/2 teaspoon kosher salt
• 1/4 teaspoon ground black pepper
• 1/4 cup milk or half-and-half
• 1 large egg yolk

• 1 tablespoon extra-virgin olive oil
• 1 yellow onion chopped
• 2 garlic cloves minced
• 1 tablespoon tomato paste
• 1 pound lean ground beef or ground lamb
• 1/2 teaspoon kosher salt
• 1/4 teaspoon ground black pepper
• 2 tablespoons all-purpose flour
• 1 cup less sodium beef broth or chicken broth
• 1 tablespoon Worcestershire sauce
• 2 sprigs fresh thyme
• 1 dried bay leaf
• 1 (10- to 12-ounce) bag frozen peas and carrots no need to thaw