Place maple syrup, soy sauce, cinnamon stick, and clove into a pot and bring to a boil.
Remove from heat and let cool. If you need to cool the marinade quickly, pour it into a bowl of ice.
Put the fish in a plastic bag. Pour cooled marinade over fish to cover and gently massage it into the fish.
Place in the refrigerator for a minimum of three hours, up to overnight.
Preheat the oven to 375 ° F/190 °C.
Clean the butternut squash. Combine cinnamon, salt and brown sugar in a bowl and sprinkle over top of the inside of the squash. Place the squash halves face down on a parchment lined baking sheet. Cook in the oven for 45 minutes. Remove the squash and allow to cool.
Remove cod from marinade and pat with paper towel to remove excess moisture.
Season the fish with salt.
Add oil and butter to an oven proof fry pan. Once hot place the fish in skin side up. Cook for two to four minutes until you develop a crust on the fish.
Remove the fish from the pan temporarily. Drain pan of butter and oil, and place the fish back into the pan, skin side down this time.
Place in fish into the oven for approximately ten minutes.
Remove the squash and allow to cool until you can remove the skin comfortably with your fingers. Scoop the flesh into a blender. Add maple syrup and orange zest. Pour in melted butter and blitz. Add water as needed to achieve silky consistency. Season to taste.
Remove the fish from the oven. It should be firm, but soft and breaking apart slightly.
Peel skin off cooked cod and plate on top of butternut squash purée.