Preheat your oven to 400 degrees.
Bring a large pot of water to a boil. Salt it like pasta water. It should be as salty as the ocean.
Wash and peel 5 lbs Yukon Gold potatoes. Cut the potatoes into similar-sized pieces for even cooking, cutting smaller potatoes in half and larger potatoes in fourths.
Add your cut potato pieces to the boiling water. Cook the potatoes for 25-30 minutes or until you can easily puncture them with a fork. Be careful not to cook your potatoes for too long or the consistency will be affected.
In the meantime, roast the garlic heads. Cut the tops off of 2 garlic heads. Wrap the garlic in aluminum foil and add salt and olive oil. Tightly seal the garlic heads and put them in the over at 400 degrees for 30 minutes.
Drain the potatoes and place the cooked potatoes back in the hot pot to dry out any excess moisture.
Mash the potatoes with a masher or the back of a fork or pass them through a potato ricer.
While you mash or rice your potatoes, add 2 1/2 cups half-and-half to a saucepan over medium heat. Add 1 sprig of thyme, 1 sprig of rosemary, and 1 sprig of sage. Infuse the herbs into the half-and-half for about 10 minutes.
Remove the sprigs of herbs from the heated half-and-half and slowly add it to your mashed potatoes little by little. The consistency will be watery at first but will thicken as it emulsifies.
Add 1 1/4 cups unsalted butter in small pieces. The hot half-and-half will melt the butter as you mix.
After you’ve added all your butter and half-and-half, squeeze the two roasted garlic heads into the mashed potatoes and mix.
Add 2 1/2 tsp kosher salt and lots of cranks of freshly ground black pepper and mix.
Garnish with more freshly ground pepper, chives, or a pat of butter. Serve and enjoy.