Light potato cake with BRUJA potatoes

Ingredients for 4 people:

5 BRUJA potatoes.
300 gr minced turkey meat.
half an onion.
Salt.
1/3 cup of milk.
1 tablespoon butter.
1 tablespoon oil.

Preparation:

Prepare a puree with the potatoes, salt, milk and butter. Take care that it does not result too watery.
Prepare some filling by stir frying the diced onion, add the minced turkey meat and cook.
Put the filling on a baking dish, add the puree above it and put to oven for 15 minutes.
You can add grated cheese or in sheets.