• Preheat oven to 400°F. Grab ingredients, then line a baking sheet with aluminum foil and set aside.
  

Make the Breadcrumbs:

• In a large bowl, combine the breadcrumbs and milk.
  2 tablespoons breadcrumbs, 2 tablespoons milk
  
• Let sit for 2 minutes to hydrate before mixing.
  
• Combine the egg, basil, garlic powder, oregano, Dijon mustard, black pepper, salt, and red pepper flakes.
  1 large egg, 1 teaspoon dried oregano, 1 teaspoon dried basil, 1 teaspoon Dijon mustard, ½ teaspoon garlic powder, ½ teaspoon kosher salt, ¼ teaspoon ground black pepper, ½ teaspoon crushed red pepper flakes
  
• Then combine with the breadcrumb mixture.
  

Make the Meatballs:

• Add the breadcrumb mixture to the ground chicken.
  1 pound ground chicken
  
• Use your fingers to gently mix together, just until combined (do not overmix).
  
• Roll into 1½-inch meatballs. Place the meatballs on the baking sheet and bake for 15-18 minutes; until the meatballs are just starting to brown and are fully cooked through.
  

Make the Sauce:

• While the meatballs are baking, prepare the sauce. Heat a large skillet on medium heat. Add marinara sauce, oregano, red pepper flakes, and salt. Heat until simmering.
  2½ cups marinara sauce, 1 teaspoon dried oregano, ½ teaspoon crushed red pepper flakes, ½ teaspoon kosher salt
  
• Reduce the heat and cook, stirring occasionally, until the meatballs are done baking, about 10 minutes.
  

Assemble:

• Spoon the meatballs into the pot of sauce.
  
• Add the kale (if using), and cook, stirring gently, until the kale has wilted.
  2 cups roughly chopped kale
  
• Top with mozzarella cheese and cook, without stirring, until the cheese has melted.
  6 ounces fresh mozzarella cheese
  
• Serve meatballs over pasta of choice or with crunchy bread.