Preheat oven to 400
After breaking garlic apart, slice the top off each head of garlic, exposing the cloves insisde
Place on aluminum foil and drizzle with olive oil
Wrap in the foil and roast until cloves are lightly browned and tender (approx. 30 minutes)
Heat heavy cream, butter and rosemary sprigs in a small saucepan over medium heat
Once butter is melted, lower heat to simmer and let sit while cooking and preparing the potatoes (the longer it simmers, the stronger the taste of the rosemary will be)
Place potatoes in large saucepan and add enough water to cover
Add 3/4 tsp salt and bring to a boil
Reduce heat to medium low , cover loosely and boil for 15-20 minutes, until potatoes break apart easily
Drain well
Using potato ricer, press potatoes in a large bowl
Add roasted garlic cloves by pressing on the bottom of a clove to push it out of its paper
Remove rosemary from cream and add cream to the potatoes
Fold cream into the potatoes until your reach the desired consistency
Less cream produces a more rustic texture while more cream will give you a smoother texture
Add salt and pepper to taste