MAKE THE INFUSED CREAM: In a small saucepan, bring the cream, thyme, and bay leaves to a slow simmer over medium heat. Turn off the heat and let the cream steep for at least 20 minutes.
Strain the cream into a medium bowl and set aside.
MAKE THE POTATOES: In a large pot, combine the potatoes, garlic, salt, and enough water to cover and bring to a boil over medium-high heat. Reduce the heat to a simmer and cook until the potatoes are fork-tender, about 15 minutes. Drain the potatoes (set the pot aside).
Working over a large bowl, in batches, if necessary, push the potatoes and garlic through a food mill fitted with the finest screen.
Add the milled potatoes back to the pot and set over low heat. Stir in the butter, followed by half the steeped cream. Then stir in a bit more of the cream, and keep adding until the potatoes just barley hold a peak when you lift the spoon. Taste for salt and add a few good cracks of black pepper. Serve immediately.
