1. Cook the Barilla® pasta for half the time indicated on the package. Drain pasta and drizzle with some olive oil to prevent from sticking. Place pasta flat on sheet trays or hotel pans and cool in a blast chiller. Alternatively, cool it down in a walk-in cooler. Store in zip lock bags or sealed plastic container; refrigerate and use within several hours.
2. Combine the milk and garlic and simmer until the garlic is soft. Drain off the milk and save it for another use.
Puree the garlic with the Parmesan and parsley. Season with salt and pepper. With the machine running, drizzle in the oil to form a pesto. Set aside.
3. Have the marinara sauce warmed and ready.
For each serving, to order: Reheat 1 2/3 oz. pasta in simmering water. Drain and toss it with 2 to 3 Tbsp. pesto. Plate 1/4 cup marinara sauce and arrange the spaghetti in a nest on top.