Preheat the oven to 350 ℉ (180 ℃) with convection (fan).
Remove the stalks from the fennel, cut it in half lengthwise and then into roughly 1/2 inch slices. Place the slices on a baking tray.
Sprinkle the garlic powder, thyme, salt and pepper on the fennel. Add the olive oil and toss to mix all the ingredients evenly. Put the baking tray in the oven.
If you are using parmesan cheese: bake for 25 minutes, then take the baking tray out, sprinkle the cheese on the fennel, and bake for 10 more minutes until the fennel is tender with brown edges.If you are not using parmesan cheese: bake for 30-35 minutes until the fennel is tender with brown edges. Optional: serve with lemon wedges on the side.
