First, prepare the instant mashed potatoes: bring the milk with butter and salt to a boil in a saucepan, then pour the potato flakes into it and mix vigorously with a whisk.
Cut salami and provolone into cubes and add them to the purée.
Cut off the cap from the peppers (after washing them well) and remove seeds and filaments without breaking the peppers.
Brush them both inside and outside with a little oil.
Fill them with the puree mixture, place them in a baking dish, cover them with the cap and cook for about 40 minutes at 180 ° C, in a preheated static oven.
The peppers stuffed with mashed potatoes are ready, you just have to serve them.