In a large skillet, heat olive oil or butter over medium heat. Add chopped onion, sauté until translucent, about 3-4 minutes. Stir in minced garlic and cook for an additional minute.

Increase heat to medium-high and add ground beef or turkey. Cook until browned, around 5-7 minutes, breaking it up while cooking. Drain excess grease if necessary.

Stir in tomato paste and Worcestershire sauce. Add dried thyme and rosemary. Pour in beef broth and simmer for about 10 minutes until thickened.

Add frozen peas, season with salt and pepper, and allow to cool slightly before transferring to a baking dish.

Boil chopped potatoes in salted water until tender, approximately 15-20 minutes. Drain and mix with butter and milk until creamy.

Preheat oven to 400°F (200°C). Spoon filling into a baking dish, dollop creamy mashed potatoes on top, and create peaks with a fork. Optionally sprinkle cheddar cheese on top.

Bake for 25-30 minutes until golden brown and filling is bubbling. Let cool for 5-10 minutes before serving.