There are really two parts to this recipe: the roasted garlic, and the mash itself. The easiest way to roast garlic is to roast a whole head of garlic; this can be done ahead of time, as you will end up with way more roasted garlic than you need. The mash is fairly straightforward; however, the cooking times of the ingredients vary slightly. Thus, in order of descending cooking time: rutabaga, butternut squash, and potato. You can either stagger the starting times for boiling them, or, as I do, adjust the size of the dice for each one. —Walker Mills
Peel most of the paper from the head of garlic, and remove the top 1/4" so that the cloves are exposed. Wrap the garlic tightly in foil, leaving the top open, and drizzle it with oil and salt, then twist the foil closed.
Bake for 45 minutes, or up to 70 minutes, depending on how roasted you like your garlic
Set a large pot of water to boil, peel the rutabaga, squash, and potato, and deseed the squash.
Small dice the rutabaga, medium dice the squash, and large dice the potato. Once the water is boiling, salt the water and add the diced ingredients. Cover and cook for 10-15 minutes, or until fork tender, then drain.
Gently heat the butter and creme fraiche until melted
Zest and juice the lemon
Mash the boiled squash, rutabaga, and potato, and mix in the roasted garlic, herbs, lemon zest, and cream & butter mixture.