Preheat the oven to 425°F. Line a large baking sheet with parchment paper.
Peel the carrots and slice diagonally into ½-inch pieces. Place them on the prepared baking sheet.
Drizzle with olive oil and season with salt and pepper. Toss until evenly coated and spread into a single layer.
Roast for 20 minutes, flipping halfway through, until the carrots begin to soften and develop golden edges.
Meanwhile, whisk together the maple syrup, Dijon mustard, minced garlic, and fresh thyme in a small bowl.
Remove the carrots from the oven and drizzle with the maple glaze. Toss until evenly coated.
Return to the oven and roast for another 8–12 minutes, until the carrots are tender and lightly caramelized.
Remove from the oven and toss with apple cider vinegar and vegan butter, if using. Garnish with additional fresh thyme and serve warm.