Part 1: Making the Creamy Mashed Potato Topping

1. Boil the Potatoes: Place the peeled and chunked potatoes in a large pot and cover them with cold, salted water by at least an inch. Bring the pot to a boil, then reduce the heat to a steady simmer. Cook for 15-20 minutes, or until the potatoes are very tender and can be easily pierced with a fork.

2. Drain and Dry: Once tender, drain the potatoes thoroughly in a colander. Return the empty pot to the low heat for a minute and add the drained potatoes back in. This helps evaporate any excess moisture, which is the key to avoiding gummy mashed potatoes.

3. Mash to Perfection: Remove the pot from the heat. Add the softened butter and mash the potatoes until the butter is incorporated. You can use a potato masher, a ricer (for the smoothest texture), or an electric hand mixer on low speed.

4. Add Dairy and Cheese: Pour in ½ cup of the warmed milk or cream and continue to mash until you reach your desired consistency, adding more liquid if needed. Stir in the shredded cheddar cheese (if using), and season generously with salt and pepper. Cover the pot to keep the potatoes warm while you finish the soup.

Part 2: Building the Savory Soup Base

1. Brown the Meat: In a large Dutch oven or heavy-bottomed soup pot, heat the olive oil over medium-high heat. Add the ground lamb or beef and cook, breaking it up with a spoon, until it is well-browned. This browning process (the Maillard reaction) is crucial for developing deep flavor. Do not rush this step. Once browned, use a slotted spoon to transfer the meat to a separate bowl, leaving the rendered fat in the pot.

2. Sauté the Vegetables: Add the chopped onion, carrots, and celery to the pot. Sauté for 7-8 minutes, stirring occasionally, until the vegetables have softened and the onion is translucent. Add the minced garlic and cook for another minute until fragrant.

3. Create the Roux and Add Aromatics: Sprinkle the flour over the cooked vegetables and stir constantly for 1-2 minutes. This cooks out the raw flour taste and creates a roux that will thicken the soup. Stir in the tomato paste, dried thyme, and dried rosemary, and cook for another minute.

4. Deglaze and Simmer: Pour in about a cup of the beef broth and use a wooden spoon to scrape up any browned bits (the “fond”) from the bottom of the pot. This is where a huge amount of flavor lives. Once the bottom is clean, slowly whisk in the rest of the beef broth and the Worcestershire sauce.

5. Combine and Cook: Return the cooked meat to the pot. Bring the soup to a boil, then reduce the heat to low, cover, and let it simmer for at least 30 minutes to allow all the flavors to meld together beautifully. The longer it simmers, the better it will taste.

6. Add Frozen Veggies: In the last 5-10 minutes of cooking, stir in the frozen corn and peas. This is just enough time to heat them through without making them mushy.

7. Final Seasoning: Taste the soup and adjust the seasoning with salt and freshly ground black pepper as needed.