In a bowl, combine the chicken with salt, garlic powder, black pepper, cumin, smoked paprika, onion powder, tomato paste, dried basil, and olive oil. Mix well and let it marinate for at least 15 minutes.
Melt the butter in a hot pan over medium heat. Add the diced onion and sauté for 2–3 minutes, until soft and translucent.
Add the marinated chicken and cook for about 3 minutes on each side, or until golden and cooked through.
Pour in the heavy cream and reduce the heat to low. Let everything simmer for about 5 minutes, allowing the sauce to thicken slightly and coat the chicken.
Spoon the creamy chicken onto your sandwich buns and top generously with mozzarella cheese. Melt the cheese with a kitchen torch, or place the sandwiches under the broiler at 190°C (375°F) for about 2 minutes, until the cheese is melted and bubbly.
Garnish with a few fresh basil leaves, if desired, and enjoy while warm!
