Prime Rib Roast with Horseradish Cream

Name: Prime Rib Roast with Horseradish Cream
Ingredients: One 10-pound, bone-in prime rib roast (about 4 bones), tied; Sea salt; Freshly ground pepper; 1/4 cup extra-virgin olive oil; 4 tablespoons unsalted butter; 2 heads of garlic, halved crosswise; 8 thyme sprigs; 2 cups crème fraîche (16 ounces); 1/2 cup grated peeled fresh horseradish; 1 tablespoon Champagne vinegar; 1 tablespoon minced chives; 1 tablespoon minced scallion; 1 teaspoon salt; 1 teaspoon cracked black pepper; 1/4 teaspoon piment d'Espelette or cayenne pepper (see Note)