Chop only 2 sweet potatoes into 1 inch chunks, then steam until tender. Place into a separate bowl and set aside.
Peel the carrot. Stand a box grater in a deep baking tray or dish, then coarsely grate the carrot, along with the celery, 2 sweet potatoes and Cheddar.
Switch to the fine side of the grater, and grate in the lemon zest. Pick and finely chop the parsley (stalks and all), and add to the tray or dish.
Add the raw peeled shrimp to the vegetable mixture.
Squeeze over the lemon juice (no seeds please!), drizzle lightly with olive oil and add a good pinch of sea salt and black pepper. If you want to add any spinach or green onions, roughly chop and add them now. Mix everything together really well in the baking pan.
Drizzle the steamed sweet potatoes with a couple of good lugs of olive oil and add a pinch of salt and pepper, then mash until nice and smooth.
Dot and spread the mash evenly over the top of the shrimp and grated vegetables. Grate some nutmeg over the top of the mashed sweet potatoes.
Bake in the oven for 40 minutes, or until cooked through, crispy and golden on top, then serve piping hot with nightshade-free ketchup, steamed veg or a lovely green salad.