Classic Shepherd's Pie

Ingredients

• 1 lb (450g) ground lamb or beef (or a mix)
• 1 medium onion, chopped
• 2 cloves garlic, minced
• 2 carrots, diced
• 1 cup (150g) frozen peas
• 1 tablespoon tomato paste
• 1 cup (240ml) beef broth (or vegetable broth)
• 1 teaspoon dried thyme
• 1 teaspoon dried rosemary
• Salt and pepper to taste
• 2 tablespoons olive oil
• 2 lbs (900g) potatoes (e.g., russet or Yukon gold), peeled and diced
• 4 tablespoons unsalted butter
• ½ cup (120ml) milk
• Salt to taste