Our first task is to boil the potatoes very well. Then, in a bowl, add 1 cup of milk along with the boiled potatoes, and blend to create a thick sauce.

In the same bowl, add the following ingredients: thyme, mustard, garlic, chopped green onion, lemon zest, salt, and finally the chicken fillet cut into strips about 1 cm thick. Mix everything well and divide it into 2 baking dishes.

Next, sprinkle some low-fat grated mozzarella on top, followed by the remaining potatoes, broken into chunky pieces. Finally, drizzle a little olive oil and place the baking dishes in the oven at 200ºC (392ºF) for 35 minutes, until they turn golden brown.