Boil the potatoes in salty water. Reserve a bit of the starchy water, like 50-100ml
Strain and put them aside
Start heating the oven to 200 C
In a deep pan, heat some olive oil and on medium-low heat sweat the onions. We want them translucent and wiggly. Add some salt and pepper to help you through the process.
When almost done, add the garlic clove and mix around for 30 seconds
Add the potatoes once the onions are ready and mix them thoroughly.
Add the starchy water or the starch with water and bring to boil.
At this point add the milk and stir. Bringing it to boil, the whole thing should have thickened a bit.
Add the whole mixture in a casserole and top it off with some shredded grana
Bake it in 200 for 15-20 minutes. As everything is cooked, we are looking for some of the liquid to evaporate and the cheese to melt properly.
