Step 1Beat the butter, rosemary, salt and lemon zest until creamy. Spoon the butter onto a sheet of plastic wrap in the shape of a log and roll it into a cylinder. Twist the ends of the plastic wrap in opposite directions to firm the cylinder and roll it gently on the counter to eliminate any air pockets in the center. Refrigerate until ready to use. This makes about ½ cup rosemary butter, more than is needed for the rest of the recipe; the butter will keep, covered and chilled, up to 2 days.
Step 1Beat the crème fraîche, black pepper, salt, lemon juice and lemon zest until creamy. Cover and refrigerate until ready to use.
Step 1Heat the oven to 350 degrees. Place the carrots on a parchment-lined rimmed baking sheet. Drizzle over a light coating of olive oil, along with ½ teaspoon salt, or to taste, and the rosemary and garlic. Toss to evenly coat with the seasoning and flavorings.
Step 2Roast the carrots until fork-tender and with little to no coloring, turning halfway through roasting for even cooking, about 35 minutes. (The carrots can be made ahead of time at this point and refrigerated up to 2 days.)
Step 3Right before serving, reheat the carrots in a sauté pan with the rosemary butter. Season with ¾ teaspoon gray sea salt, or to taste. Remove from heat and toss the carrots with 1½ teaspoons maple sugar, or to taste.
Step 4Place the carrots on a serving platter and drizzle over the crème fraiche and a sprinkling of chives for garnish.