Start by preheating your oven to 400°F (204°C). Line a baking sheet with parchment paper or give it a light coat of nonstick spray. Having everything ready before you start mixing makes the whole process feel less chaotic and keeps your hands cleaner.
In a large bowl, combine the ground chicken, egg, olive oil, Worcestershire sauce, breadcrumbs, parmesan, garlic, and seasonings. I use my hands here since it mixes more evenly than a spoon, but gentle overmixing makes meatballs tough instead of tender.
Using a cookie scoop or tablespoon, portion the mixture into balls about 1.5 inches wide. Roll them loosely in your palms; this should give you roughly 35 meatballs. Place them on your prepared baking sheet with a little space between each one.
Slide the tray into your preheated oven and bake for about 20 minutes. The meatballs are done when an instant-read thermometer reads 165°F (74°C) in the center. This is the one step I never skip, since guessing by color alone isn't reliable.
While the meatballs bake, melt the butter in a small saucepan over medium-low heat. Stir in the garlic and cook for about a minute until fragrant. Remove from heat and whisk in the lemon juice, herbs, and a pinch of salt.
As soon as the meatballs come out of the oven, brush or spoon the warm garlic butter sauce over them. Sprinkle with red pepper flakes if you like a little heat, and serve immediately while they're still warm and glossy.