Begin by coating boneless chicken breasts with a drizzle of oil and your favorite seasonings. Preheat your grill over medium-high heat, then grill the chicken for 6-8 minutes per side until fully cooked. Remove from heat, let rest, then cube.

In the same pan, add more oil if necessary and sauté finely chopped onion over medium heat for 3-4 minutes until golden. Add minced garlic and cook for another 1-2 minutes. Sprinkle in flour, stirring constantly for about a minute.

Gradually pour in milk and heavy cream, whisking steadily until it thickens into a creamy sauce.

Stir in grated Parmesan cheese until melted, then fold in chopped spinach until it wilts slightly.

Preheat your oven to 400°F (200°C). Lightly toast your flatbread until warm. Spread the creamy sauce over the flatbread, add grilled chicken, and sprinkle mozzarella cheese on top.

Place the flatbread on a baking sheet and broil for 2-3 minutes until the cheese is bubbling and golden brown.

Let the flatbread cool for a minute, slice, and serve hot.