Preheat oven to 435°F.

Place potatoes on baking sheet and rub with olive oil and salt. Bake until fork tender about 1 hour. Remove from the oven and allow to cool completely.

For the filling, set a large skillet over medium-high heat. Add the ground beef and begin breaking it up with a wooden spoon. Add the onion, leek, celery, carrots, ½ teaspoon salt, ¼ teaspoon pepper and paprika, if using. Cook, stirring occasionally, until the celery and carrots start to soften, about 7 minutes. Add the minced garlic and tomato paste and stir constantly until the mixture darkens and the garlic is fragrant, about 2 minutes.

Add the butter and allow to melt. Sprinkle the flour over the vegetables and stir to combine. Cook, stirring constantly for about 2 minutes, scraping up the browned bits on the bottom of the skillet. Add the beef broth, Worcestershire sauce, parsley, rosemary and thyme. Scrape the bottom of the pan to release any browned bits and bring to a boil, still over medium heat. Reduce the heat to medium-low and spread out the vegetables evenly. Add the beef in small portions on top of the vegetables. Bring the mixture to a simmer, cover and cook until the beef is cooked through, about 12 to 15 minutes, stirring regularly to break up any large clumps.

Whisk together the cornstarch with 1 tablespoon water and add it to the beef. Cook for 1 minute or until slightly thickened. Stir in the peas and remove the skillet from the heat. Check the seasoning and add salt and pepper as needed. The filling can be made ahead and stored in the fridge till needed. Return to room temperature before assembling.

Once potatoes have cooled, scoop out the filling and place in a bowl. Add the butter, milk, salt, pepper, and cheddar cheese. Blend with a fork until combined.

Place the potato shells onto a baking sheet. Fill with the meat mixture and then top with the mashed potatoes. Bake in 375°F oven until golden brown, about 20 minutes. Top with chives, parsley or thyme. Serve and enjoy!