Sweet Potato Shepherd's Pie

Ingredients

• 1 tablespoon olive oil (15 ml)
• 1 large onion, chopped (about 1 ½ cups)
• 2 carrots, peeled and diced (about 1 cup)
• 2 celery stalks, diced (about ¾ cup)
• 1 pound (450g) ground beef (preferably 80/20)
• 1 teaspoon dried thyme
• 1 teaspoon dried rosemary
• ½ teaspoon smoked paprika
• ½ teaspoon salt, plus more to taste
• ¼ teaspoon black pepper, plus more to taste
• 2 tablespoons all-purpose flour (30g)
• 1 cup beef broth (240 ml)
• ½ cup frozen peas
• ½ cup frozen corn
• 2 tablespoons tomato paste (30 ml)
• 1 tablespoon Worcestershire sauce (15 ml)
• 2 pounds (900g) sweet potatoes, peeled and cubed
• 4 tablespoons (57g) unsalted butter
• ½ cup milk (120 ml)
• ¼ cup chopped fresh parsley
• 2 tablespoons chopped fresh chives
• Salt and pepper to taste