Cook penne according to package directions. Rinse pasta under cold water until cool. Drain well.

Meanwhile, stir the mayonnaise with the buttermilk, cheese, lemon juice, Worcestershire sauce, anchovy paste (if using), Dijon mustard, garlic, and lemon zest until well combined. Reserve.

Preheat the grill to medium high. Toss the chicken with 1/4 cup (50 mL) of the dressing mixture and season with salt and pepper.

Grill the chicken for 5 minutes. Turn the chicken breasts and reduce the heat to medium. Cook chicken for an additional 6 to 8 minutes or until an instant-read thermometer reads 165ºF (74ºC) when inserted into the thickest part of the meat. Remove chicken from the grill. Rest for 5 minutes, then slice thinly.

Toss the cooled pasta with the remaining mayonnaise mixture, sliced chicken, bacon and tomatoes. Sprinkle with additional Parmesan, salt and pepper to taste. Garnish with parsley.

Tips
For a quick pantry substitute, use 1 1/2 cups (375 mL) purchased Caesar salad dressing instead of the homemade version.
Replace the buttermilk with “sour” regular milk by stirring with one quarter of the lemon juice; let stand for 5 minutes before adding to the remaining dressing ingredients.