Go Back
Pesto bruschetta chicken sandwich with caramelized onions, melted mozzarella, and pesto tomatoes on a brioche bun

Pesto Bruschetta Chicken Sandwiches

Seared chicken piled with jammy caramelized onions, melty fresh mozzarella, and pesto-balsamic marinated tomatoes on a toasted brioche bun with pesto aioli. A sandwich that eats like a meal.
Print Recipe Pin Recipe
Prep Time 20 minutes
Cook Time 25 minutes
Total Time 45 minutes
Servings: 4 sandwiches
Course: Main Course
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

  • 2 large boneless skinless chicken breasts butterflied (or 4 thin-cut chicken fillets)
  • 4 brioche hamburger buns
  • 2-3 Tbsp butter softened, for the buns
  • 2 large Roma tomatoes sliced about 1/4" thick
  • 1 large red onion very thinly sliced (a mandoline makes this easy)
  • 1/3 cup basil pesto divided
  • 2 cloves garlic minced
  • 2 Tbsp thick balsamic vinegar or balsamic glaze
  • 1/2 cup mayonnaise
  • 8 oz fresh mozzarella sliced
  • olive oil for the skillets
  • salt, black pepper, and garlic powder to taste

Equipment

  • 2 Large Skillets
  • Baking Sheet
  • Mandoline Slicer optional, for the onions
  • Instant-Read Thermometer

Method
 

Prep
  1. Make the pesto aioli: stir the mayonnaise and half the pesto together until smooth. Taste and add more pesto if you like. Cover and set aside.
  2. Marinate the tomatoes: gently toss the tomato slices with the minced garlic, the rest of the pesto, and the balsamic. Cover and refrigerate while you cook (15 minutes minimum, longer is better).
  3. Preheat the oven to 375°F. Butter the cut sides of the buns and set them cut-side up on a baking sheet.
Cook (Two Skillets at Once)
  1. Heat a little olive oil in two large skillets over medium-high heat.
  2. Onions first: add the onions and a small pinch of salt to one skillet. Cook about 10 minutes, stirring now and then, until soft and caramelized. A few charred bits are a good thing.
  3. Chicken: while the onions cook, season the chicken on both sides with salt, pepper, and garlic powder. Sear in the second skillet until just cooked through (165°F inside), about 4-5 minutes per side for thin pieces.
  4. Buns: slide the buns into the oven to toast for 5-8 minutes while the chicken and onions finish. Pull them out and switch the oven to broil.
Melt & Assemble
  1. Move the chicken to a foil-lined baking sheet. Top each piece with a scoop of onions, then a couple slices of mozzarella.
  2. Broil 2-3 minutes, watching closely, until the cheese is melted and bubbly.
  3. Spread pesto aioli on both halves of each toasted bun. Add the chicken to the bottom bun, lay a couple marinated tomato slices on top, add the top bun, and eat it while it's hot.

Notes

One-skillet version: cook the chicken first, set it aside, then cook the onions in the same pan. Fewer dishes, but the chicken cools a bit while the onions go. The broiler step warms it back up.
No broiler? Put the topped chicken back in a hot skillet, add a few tablespoons of water, and cover for a minute or two to steam the cheese melted.
Use a thick balsamic. Thin, watery vinegar just runs off. If yours is thin, grab a store-bought balsamic glaze.
Feeding a crowd? The broiler method handles 6+ pieces of chicken at once, which is how I usually do it.
Prettier option: balsamic-marinated tomatoes taste great but look a little dark. For guests (or photos), toss the tomatoes with just pesto and garlic and drizzle the balsamic over the top instead.
🛒 Shop the gear I used in this recipe