Preheat your oven to 400°F before you start mixing anything. Spray a baking sheet with nonstick cooking spray or line it with parchment paper. Having this ready means you can move straight from mixing to baking without the meatballs sitting out too long.
Add the ground chicken, parmesan, breadcrumbs, eggs, milk, basil, garlic, salt, and pepper to a large bowl. Mix everything with your hands or a wooden spoon just until combined, working from the outside in so nothing sticks to the sides. I always stop mixing the second it looks even, since overworking the meat makes it tough instead of tender.
Grab your 2 ½ tablespoon cookie scoop and portion out the mixture so every meatball starts off the same size. Roll each portion gently between your palms into a smooth ball, without pressing too hard or squeezing out the moisture. Place them on the prepared baking sheet with a little space between each one so they cook evenly on all sides.
Slide the baking sheet into the oven and bake for about 15 minutes. Check that the internal temperature has reached 165°F with a meat thermometer before pulling them out. If you want extra color, broil for the last 2 to 3 minutes while watching closely.
Once they're out of the oven, let them rest for a minute or two before serving. Toss them in marinara, add them to a wrap, or serve them plain with a dipping sauce on the side. This is the point where you get to make the recipe your own.