Steam your broccoli until tender, then finely chop it (or pulse it in a food processor) so it incorporates smoothly.
In a large bowl, combine the ground chicken, chopped broccoli, oat flour, shredded cheese, egg, garlic powder, onion powder, salt, and pepper. Mix until everything is well combined.
Scoop about two tablespoons of the mixture at a time and form it into a nugget shape and slightly flatten.
Arrange on a parchment-lined baking sheet and bake at 400°F for 10-15 minutes.
Nuggets are done when the internal temperature reaches 165°F and the cheese is melted and bubbly.