Heat the olive oil in a large pot or Dutch oven over medium heat. Add the onion, carrots, and celery, and sauté for 5-7 minutes until softened.

Stir in the minced garlic and cook for an additional 1 minute until fragrant.

Add the ground lamb (or beef) to the pot, breaking it up with a wooden spoon. Cook until browned, about 5-7 minutes. Drain any excess fat if necessary.

Season the mixture with salt, black pepper, thyme, and rosemary. Stir in the tomato paste and cook for 1-2 minutes to incorporate the flavors.

Pour in the beef broth and bring the mixture to a simmer. Add the diced potatoes and cook for 15-20 minutes, or until the potatoes are tender.

Stir in the frozen peas and corn, cooking for an additional 5 minutes.

Reduce the heat to low and stir in the heavy cream and butter. Allow the soup to gently simmer for 2-3 minutes, then taste and adjust seasoning with additional salt and pepper if needed.

Serve hot, garnished with fresh chopped parsley if desired.