Preheat oven to 375 degrees.
Clean the peppers and cut in half. Place in a roasting pan lined with foil and cooking spray.
Heat a skillet over medium heat with 1 Tbsp. olive oil. Add the shallots and saute until softened; about 3 minutes. Add salt/pepper.
Add the garlic and cook for another minute or 2.
Add the lamb and gently brown stirring into bite-sized pieces.
Once the lamb is browned, add the frozen veg, beef broth, Worcestershire sauce and fresh rosemary. Stir until the vegetables start to thaw and ingredients are well combined.
Thicken the sauce by adding a Tbsp. of flour. Stir to combine and simmer for about 5 more minutes or until the sauce begins to look like a nice gravy. Taste again for seasoning. Remove from the heat.
Stuff the peppers by spooning the warm mixture into each hollowed out pepper until the meat/veg mixture nearly reaches the top of the Bell pepper.
Top with mashed potato piled high; ab out 1/2 cup per pepper. Sprinkle cheddar cheese and lightly add some dried thyme.
Bake at 375 degrees for 30 to 35 minutes until the peppers are crisp-tender and the tops are golden brown.