Sauce
In a large baking sheet, start by adding the sliced onions and spread them across the bottom of the baking sheet.
Add the potatoes cut into thin slices, covering the onions.
Season with salt to taste and a pinch of black pepper.
Then, add the skinless chicken thighs and set aside.
In a small bowl, add the olive oil, the milk, the tomato paste, the salt, the black pepper, the sweet paprika and mix everything together very well until the spices incorporate.
Pour this sauce all over the chicken thighs and using a brush, spread it very well over all the thighs and potatoes.
Take to a preheated oven at 180° C (350° F) and bake for 35 minutes.
Serve.