Preheat the oven to 200°C.
Squeeze excess water from grated potatoes using a clean tea towel.
Mix potatoes with crème fraîche, egg yolk, salt, and pepper.
Melt butter in an oven-proof pan and place 7.5cm metal rings inside.
Spoon potato mixture into rings and cook for 4 minutes per side until golden.
Bake the rostis in the oven for 10 minutes until cooked through.
Sear duck skin-side down for 3 minutes, then bake for 5 minutes.
Rest the duck for 5 minutes after removing from the oven.
Sauté shallots in butter until softened.
Add Madeira and reduce by half, then simmer with cherries and chicken stock for 5 minutes.
Whisk in redcurrant jelly and season with salt and pepper.
Wilt spinach in a hot pan with butter and season with nutmeg.
Serve sliced duck over rosti and spinach, topped with cherry sauce.