When you start cooking the chicken, line a sheet pan with non-stick aluminum foil and add the fennel wedges and the remaining half lemon cut in two. Drizzle vegetables with marinade, season with kosher salt and black pepper and add 1/4 cup water.
Cover fennel with a sheet of aluminum foil and place in a pre heated 375°F oven. Bake for 15 minutes, or until the fennel is soft when pierced with a fork.
When done, remove aluminum foil and add whole spring onions, increase heat to 400°F and bake for another 15 minutes.
Transfer frozen peas to a microwave safe dish, cover with cling wrap and microwave on high for 1-2 minutes, or until the peas are hot and tender.