Prepare the agretti: Clean the agretti thoroughly. In a pan, heat a drizzle of extra virgin olive oil with the fresh chili pepper and garlic cloves. Sauté the agretti for a few minutes until tender, then set aside.
Make the meatball mixture: In a bowl, combine the ground veal, grated cheese, salt, black pepper, milk, finely chopped chives, and the egg. Mix well to combine.
Form and cook the meatballs: Shape the mixture into small balls. In the same pan used for the agretti, heat some olive oil and brown the meatballs on all sides until they are well colored and cooked through.
Prepare the mustard mayonnaise: In a blender or mixer, emulsify oil and egg to make mayonnaise. Then add Dijon mustard, whole grain mustard, salt, and a splash of lemon juice. Mix well and transfer to a piping bag.
Plate and serve: Arrange the sautéed agretti on plates, place the meatballs on top, and garnish with mustard mayonnaise. Serve immediately.