Preheat oven to 375F.

Make croutons. In a small bowl, combine the Italian seasoning, garlic powder, and a pinch of salt, if needed. Cut the bread slices into 6 or 8 pieces each and place on a parchment-lined baking sheet. Drizzle the olive oil over the bread and toss. Sprinkle the spice blend over the bread pieces and toss again. Put the baking sheet in the oven and bake for 10 minutes. Flip or toss the croutons and continue baking for an additional 10 minutes, until brown on all sides. Remove the baking sheet from the oven and set aside.

Make the chicken. In a small bowl, combine the italian seasoning, salt, and pepper. Rub every crevice of each chicken breast generously with olive oil, then sprinkle with the spice mixture. Bake for 35-40 minutes, depending on the size of your chicken breasts, then brush the top of the chicken with the juices. Return to the oven for 5 minutes to brown. Remove from the oven. (If it isn’t brown enough at this point, baste again, turn up the oven temp, and bake for another 5 minutes.) Let the chicken breasts rest for 10 minutes, then cut into cubes and set aside.

While the chicken is resting, make the giardiniera mayo. Chop the giardiniera into fine pieces and add to a small bowl along with the mayo. Stir until well-combined. Alternatively, you can add the mayo and giardiniera to a food processor and process until your desired consistency. Set aside.

Assemble your jars or bowls. Add a teaspoon of marinated onion oil and some marinated onion rings to the bottom of each jar then top with some celery and a handful of lettuce. Place some cubed chicken breast on the lettuce and top with some of the giardiniera mayo. Layer each jar with a quarter of the salami, provolone, and cherry tomatoes. Top each jar with a small handful of croutons and a peperoncini. Enjoy!