Prepare all ingredients as listed.
In a small bowl, mix the mayonnaise, chopped chipotle chile, adobo sauce to taste, kosher salt, and black pepper until smooth and well combined.
Brush the cut sides of the focaccia lightly with olive oil. Spread the chipotle mayo evenly over the inside of each piece of bread.
Layer the sandwiches with fresh basil, shredded chicken, mozzarella, tomato slices, and red onion. Salt and pepper to taste. Close the sandwiches firmly.
Preheat a panini press or grill pan. Place the sandwiches inside and cook until the focaccia is crisp and golden brown on both sides and the mozzarella is fully melted, about 5–7 minutes.
Combine the sparkling water, lemon slices and chia seeds. Stir thoroughly, let sit for 2–3 minutes, then stir again to prevent clumping.
Serve the Frontega chicken panini alongside carrot sticks, hummus, and lemon chia sparkling water.