In a Dutch oven or large pot, add olive oil and 1 tablespoon of butter. Heat over medium heat.

Add carrots and celery to the pot and sauté for 5 minutes.
Next add the onions, herbs, salt, pepper and sauté until onions begin to become translucent - about 5 minutes.

Add the ground lamb and ground beef to the pot with the vegetables and cook until browned.

Move the vegetables and meat to the side of the pot and add the flour. Cook for a minute or two to take away that "flour taste".

Add the beef broth, wine, Worcestershire sauce, and tomato paste in and mix everything together. It will start to thicken after a moment.

Turn the heat down to simmer for 10 minutes.
Turn the heat off and stir in frozen peas. Cover the pot until ready to add to the casserole dish.

Prepare the Mashed Potato Topping: Peel, rinse and dice potatoes. Add them to a pot and cover with water for boiling. Bring to a boil over high heat. Once the potatoes begin to boil, reduce heat and cook for 20 minutes.

Preheat oven to 375°F

Add softened butter to a mixing bowl. Measure out heavy cream and set aside. Measure out fresh grated white cheddar and set aside. When the cooking time is finished for the potatoes, drain well in a colander. Add potatoes to the mixing bowl with the butter.
With a hand mixer, whip potatoes on high for a minute or two.
Add heavy cream, cheese, salt and pepper and whip on high until creamy.

Lightly spray a casserole dish and add meat and vegetable mixture. Top with mashed potatoes.

Bake until the potatoes begin to brown on top - 20 to 25 minutes.

Allow the Shepherd's Pie to rest for five minutes after you remove from the oven before serving.