Place the carrots, onions, and garlic on a baking sheets. Drizzle with olive oil and toss to coat. Sprinkle with salt and pepper.
Bake for 15 minutes. Remove from oven, sprinkle with thyme and rosemary and toss to mix. Continue cooking for 10-15 minut4es or until the carrots begin to caramelize in the oven.
Remove from oven and drizzle with lemon juice. Toss to coat. Serve hot.