Burgers with Mozzarella and Spinach-Arugula Pesto

• 8 ounces baby spinach leaves (about 10 cups packed)
• 2 garlic cloves, peeled
• 1/2 teaspoon (packed) finely grated lemon peel
• Large pinch of dried crushed red pepper
• 4 cups (packed) fresh arugula leaves, divided (about 5 ounces)
• 3 tablespoons pine nuts
• 1 teaspoon fresh lemon juice
• 1/3 cup extra-virgin olive oil
• 3 tablespoons (packed) freshly grated Parmesan cheese
• 1 3/4 pounds ground beef (20% fat)
• 1 teaspoon salt
• 1/2 teaspoon ground black pepper
• 6 hamburger buns, split horizontally
• 6 1/3-inch-thick slices fresh mozzarella cheese
• 2 large beefsteak tomatoes, cut into 1/4-inch-thick rounds

1. Rinse spinach; drain briefly, then place in large glass bowl.
2. Microwave spinach, uncovered, on high just until wilted, 1 to 1 1/2 minutes.
3. Drain, then squeeze out as much liquid as possible.
4. Combine garlic, lemon peel, and crushed red pepper in processor; blend until garlic is finely chopped.
5. Add spinach, 2 cups (packed) arugula, pine nuts, and lemon juice; process until coarse puree forms.
6. With machine running, gradually add oil in thin stream and blend until almost smooth.
7. Mix in cheese.
8. Transfer pesto to small bowl; season with salt.
9. Do ahead: Can be made 6 hours ahead.
10. Cover; chill.
11. Combine ground beef, 1 teaspoon salt, 1/2 teaspoon black pepper, and 6 tablespoons spinach-arugula pesto in large bowl; mix lightly with fingertips or fork just until incorporated.
12. Form meat mixture into six 3/4-inch-thick patties.
13. Place patties on platter.
14. Do ahead: Beef patties can be made 6 hours ahead.
15. Cover and refrigerate.
16. Prepare barbecue (medium-high heat).
17. Grill burgers to desired doneness, about 4 minutes per side for medium-rare.
18. Grill buns, cut side down, just until lightly toasted, about 1 minute.
19. Build burgers with pesto, patties, mozzarella cheese, tomatoes, and arugula.
20. Cover with bun tops.

baby spinach, garlic, lemon peel, red pepper, arugula, pine nuts, lemon juice, extravirgin olive oil, parmesan cheese, ground beef, salt, ground black pepper, buns, mozzarella cheese, beefsteak tomatoes

Taken from www.epicurious.com/recipes/food/views/burgers-with-mozzarella-and-spinach-arugula-pesto-235619 (may not work)