Preheat a grill on low heat.
Butterfly tenderloin, rub with olive oil, and spread with garlic pesto. Add the spinach, basil and cheeses. Season with salt and pepper, to taste. Wrap bacon around tenderloin and secure with wood skewers presoaked in water.
Grill for 35 to 40 minutes on low heat. Let rest for 5 to 10 minutes.
Top with more cheese and serve immediately.