Preheat the oven to 300 degrees. Rinse the head of garlic and cut off the top, exposing the cloves. Season the exposed edges with salt and pepper and place facedown in a deep baking dish.
Add the olive oil, peppercorns, and fresh thyme to the baking dish, cover with aluminum foil, and roast for one hour. Remove from the oven and let cool for 30 minutes, covered.
Uncover and remove the garlic, placing on a towel to drain. Strain the oil through cheesecloth and into an 8 oz Mason jar, adding one fresh sprig of thyme.
Squeeze the cloves of garlic from the head and add them to the Mason jar. The infusion and roasted garlic cloves will keep in the refrigerator for up to one month.
Note: Don’t let the roasted garlic cloves in this infusion go to waste! Use them along side the infused oil. They have an amazing caramelized, umami-packed richness!