Little Italy Burger

INGREDIENTS

• 1 ½ lbs. ground beef
• 8 slices pancetta
• 1 jar of good pesto
• 1 large ball smoked mozzarella
• 1 red onion, cut into thin rounds
• 3 Tb. butter
• 2 tsp. tomato paste
• 1 tsp. anchovy paste
• Baby arugula
• Ripe tomato slices
• 4 ciabatta buns
• Basic Pesto:
• 2 cups packed fresh basil leaves
• 2 cloves garlic
• 1/4 cup pine nuts
• 2/3 cup extra-virgin olive oil, divided
• Kosher salt and freshly ground black pepper, to taste
• 1/2 cup freshly grated Pecorino cheese