Add the apple cider to a small saucepot and place over medium-high heat. Bring to a boil and continue to cook until reduced to 1/3 cup, about 15 minutes. Set aside.
Preheat the oven to 475 degrees F.
Cut the tops of the fennel bulb and coarsely chop 2 tablespoons of the delicate frond leaves from the tops. Leaving the root end intact, cut the fennel bulb into 8 slices, lengthwise. Add the fennel to a large bowl and drizzle with the oil and 2 tablespoons of the reduced apple cider, tossing to coat. Add the rosemary, thyme and a generous pinch of salt and pepper and toss to combine. Arrange the fennel in a single layer on a baking sheet with space between each wedge. Roast until the fennel begins to brown, about 15 minutes, then flip the wedges and continue to roast until tender and browned on both sides, about 10 minutes more.
Add the fennel to a serving dish and drizzle with the rest of the apple cider reduction and a sprinkle of fennel fronds. Serve warm.