Peel and chop the potatoes into chunks. Add them to a pot of salted boiling water, and cook them for 20 minutes until soft.
Sizzle the mushrooms in a skillet with oil, smoked paprika, and garlic.
Blitz a handful of cooked potatoes in a blender with a pinch of nutmeg, black pepper, and salt into a smooth and stretchy mix.
Mash the remaining potatoes with parsley, salt, pepper, and nutmeg. Then, incorporate the mushrooms.
Roll a small handful of mash into a ball. Then, use your pinky finger to poke a hole in the centre.
Fill a piping bag with the potato cream and pipe it into the hole. Then, seal the croquette with a bit of mash.
Soak the flaxseeds in water for 10 minutes. Dip each potato ball twice, first in the flax mix and then in the breadcrumbs.
Bake the croquettes at 220°C (430°F) for 25 minutes until the coating is crusty and golden.