Preheat oven to 400 degrees. Slice off the top of the head of garlic, place on a sheet of aluminum foil and drizzle with olive oil. Wrap the garlic in the aluminum foil and place in the oven to roast for 30 - 35 minutes.

Fill a large saucepan or stock pot with water and bring to a boil. Add potatoes and reduce heat to medium-high. Boil for 15 - 20 minutes, until potatoes are tender.

While potatoes are cooking, place the bison or lamb in a skillet, add salt, pepper and nutmeg and saute until brown. Transfer to a bowl.

In the same skillet, add onions and saute until tender. Add olive oil if needed. Add mushrooms and carrots and saute for 3-4 minutes. Add frozen peas. Transfer meat back into the skillet, cover and continue to simmer on medium heat.

Drain potatoes and place in a large bowl. Remove the garlic head from the oven and carefully squeeze the garlic head (using a potholder) forcing the roasted garlic out into the bowl. Whip potatoes with electric mixer, adding vegetable broth until potatoes reach desired texture. No need to remove the skins, just blend them right in. Add salt and pepper to taste.

Place meat and vegetable mixture into 9" x 12" pan or deep pie dish and spread potatoes over the top.

Switch oven to broil, place dish into the oven and heat until potatoes begin to brown (5-7 minutes).