In a food processor, combine basil leaves, garlic, pine nuts, Parmesan cheese, kosher salt, and black pepper. Pulse until finely chopped, then drizzle in olive oil while blending until smooth. Set aside.

In a medium bowl, mix shredded chicken with the prepared basil pesto and Greek yogurt until evenly coated. Season with additional salt and pepper if necessary.

Preheat your oven to 350°F (175°C). Slice the baguettes in half and toast in the oven for 5–7 minutes until golden and crisp.

Layer the bottom half of each toasted baguette with arugula, tomato slices, and mozzarella cheese.

Scoop the chicken pesto mixture onto each baguette, spreading it evenly. Close each sandwich with the top half of the baguette.

Serve immediately while warm for the best flavor and texture.