First, you'll caramelize the onions, bringing out their natural sugars. Then, you cook the chicken and assemble the flatbread with two perfect elements: melty mozzarella and juicy grape tomatoes. Bake, top with pesto and arugula, and presto! Pesto chicken pizza.
Halve and peel onion. Slice halves into thin strips. Halve grape tomatoes. Pat chicken breasts dry. On a separate cutting board, cut chicken into 1” dice. Season with a pinch of salt and pepper.
Caramelize the Onion
Heat 2 tsp. olive oil in a medium non-stick pan over medium heat. Add onion to hot pan and stir occasionally until tender and lightly charred, 10-12 minutes. Transfer onion to a plate and set aside. Reserve pan; no need to wipe clean.
Cook the Chicken
Return pan used to caramelize onion to medium-high heat. Add 2 tsp. olive oil and chicken to hot pan and cook undisturbed until browned on one side, 3-4 minutes. Stir chicken and cook until chicken reaches a minimum internal temperature of 165 degrees, 2-3 minutes. Remove from burner.
Assemble the Pizzas
Drizzle each flatbread with ¼ tsp. olive oil and season with a pinch of salt and pepper. Divide chicken between each flatbread, followed by mozzarella, grape tomatoes, and caramelized onion.
Bake the Pizzas
Place assembled pizzas directly on top oven rack. Place prepared baking sheet on rack below to catch any drips. Bake until crust is golden brown, and cheese is melted, 7-10 minutes. Remove from oven and rest 5 minutes. Garnish rested pizzas with pesto and arugula.