Step 1

Arrange a rack in the upper third of the oven and heat the oven to 425°F. Line a rimmed baking sheet with parchment paper or aluminum foil coated with cooking spray.

Step 2

Mince 4 garlic cloves. Pick the leaves from 1/2 medium bunch fresh parsley and finely chop until you have 1/2 cup. Finely grate 2 ounces Parmesan cheese (about 1/2 cup).

Step 3

Place half of the garlic, half of the Parmesan cheese, all of the parsley, 1/2 cup panko breadcrumbs, 1/4 cup of the half-and-half, 1 large egg, 1 1/4 teaspoons of the kosher salt, 1/2 teaspoon onion powder, and 1/4 teaspoon black pepper in a large bowl. Stir until combined.

Step 4

Add 1 1/2 pounds ground chicken and mix until evenly combined; do not overmix or the meatballs will be tough. Scoop out the mixture in heaping 2-tablespoon portions (about and roll between damp hands until a smooth ball forms. Place on the baking sheet, spacing them evenly apart.

Step 5

Roast until cooked through and an instant-read thermometer inserted in the center of a meatball registers at least 165°F, 12 to 15 minutes. Meanwhile, make the sauce.

Step 6

Melt 2 tablespoons unsalted butter in a 12-inch frying pan or skillet over medium heat. Add the remaining garlic, 2 tablespoons all-purpose flour, 1 teaspoon Italian seasoning, 1/4 teaspoon red pepper flakes, and remaining 1/4 teaspoon kosher salt. Cook, stirring constantly, for 30 seconds to cook the floury taste out.

Step 7

Add the remaining 3/4 cup half-and-half and 1 1/2 cups low-sodium chicken broth. Whisk until smooth and bring to a boil. Reduce the heat to maintain a simmer and cook, whisking occasionally, until the sauce thickens slightly and coats the back of a spoon, 4 to 5 minutes.

Step 8

When the meatballs are ready, turn on the broiler and broil until the meatballs are browned, 2 to 3 minutes.

Step 9

Add 4 ounces baby spinach and the remaining Parmesan to the sauce, and stir until the spinach just begins to wilt, about 30 seconds.

Step 10

Transfer the meatballs to the sauce and gently stir to coat. Garnish with more grated Parmesan if desired.