- Combine all ingredients except oil in a blender or food processor and blend until pureed.
- Add oil slowly in a stream until fully combined. Set aside.
- Heat spinach on a microwave-safe plate for one minute; set aside to cool.
- Transfer to double layer of paper towels; fold over and squeeze excess moisture from spinach.
- Combine spinach, onions, vinegar, Worcestershire, salt and peppers in blender or food processor and process until finely minced.
- Transfer mixture into a mixing bowl with ground chicken and bread crumbs; stir until well combined.
- Form into 12 golf ball-sized meatballs.
- Heat oil in a 12-inch nonstick skillet over medium-high heat.
- Arrange meatballs in skillet and cook for 6 to 8 minutes turning meatballs until browned and cooked through.
- Spread pesto onto both halves of each slider rolls, add desired toppings and one meatball per roll.
- Serve immediately.
Slightly flatten each meatball for quicker cooking and easier eating!