Preheat oven to 400 degrees F. Line a baking sheet with parchment paper or foil.
Place carrots, garlic and thyme on the prepared pan. Drizzle with 2 tablespoons oil and season with 1/4 teaspoon salt; toss to coat. Roast until the carrots are tender but not browned, 25 to 30 minutes. Discard the thyme.
Meanwhile, to prepare dukkah: Heat a small skillet over low heat. Add pistachios, sesame seeds, coriander, cumin and the remaining 1/8 teaspoon salt; cook, stirring constantly, until warm and fragrant, 2 to 4 minutes. Remove from heat.
Arrange the carrots and garlic on a platter. Drizzle with the remaining 1 tablespoon oil and sprinkle with the dukkah. Serve warm.