To prepare the potato and bacon pie, first cut the bacon into strips and then into cubes; then remove the peel from the onion and cut it into thin slices; peel the potatoes and cut them into thin slices 4-5 mm with a mandolina or with a knife.
As you cut the potatoes, place them in a bowl with cold water to prevent them from blackening.
Put the bacon cubes in a pan, preferably non-stick, and brown them over low heat; add the onions and let them cook over low heat for about twenty minutes with the bacon.
To flavor at the end of cooking, add salt, pepper and a few sprigs of thyme to taste.
While the sauce is cooking, blanch the potatoes in boiling water with a little salt and after about 4 minutes put them to dry on a tray with kitchen paper or absorbent paper.
Prepare the bechamel
To prepare the bechamel, heat the milk in a saucepan and, in the meantime, melt the butter in a pan over low heat.
When the butter is melted, remove the pan from the heat and add the flour, stirring immediately with a whisk to avoid the formation of lumps; then put the pan back on low heat to toast the flour.
After this step, pour in the hot milk and continue stirring over low heat. To give the béchamel more flavor, add a little grated nutmeg.
Compose the potato and bacon pie
To compose the potato and bacon pie, take a Fiamminga (pan) or a 30 × 22 pan and sprinkle the bottom with one or two tablespoons of bechamel.
Then put the first layer of potato slices, then the pancetta and a handful of grated Asiago; cover with the béchamel and repeat for all the layers.
To the last layer, add a topping of béchamel and, to add flavor, a few leaves of fresh thyme.
Then cook the pie in a static oven preheated to 180 ° C for 45 minutes or, if you prefer, in a convection oven at 160 ° C for 35 minutes.
Once cooked, let it cool slightly before serving.