In a medium-sized bowl, add the ground turkey, minced garlic, onion powder, black pepper, Worcestershire sauce, kosher salt, smoked paprika, cumin, and chopped spinach. Mix well with a spoon or clean hands.
Form 8 slider patties with the chopped spinach and ground turkey. Transfer to a large plate. Wrap the plate with plastic wrap and refrigerate the patties for 30 minutes or overnight. (This process is not necessary, but will prevent the patties from falling apart during cooking.)
Preheat a gas grill or cast iron skillet. Grill the sliders over medium heat for 3 to 4 minutes per side or until the burgers reach 165 degrees F.
Deck-out your spinach and turkey burger sliders with your favorite toppings (tomato, lettuce, pickles, ketchup, mustard, etc.) and serve hot.