Preheat the oven to 375°F and lightly grease a loaf pan with the olive oil.
In a large bowl, combine the ground chicken, finely chopped broccoli, shredded cheddar cheese, breadcrumbs, egg, finely chopped onion, minced garlic, salt, and black pepper.
Mix the ingredients with clean hands or a spoon until evenly combined, taking care not to overwork the mixture.
Transfer the mixture to the prepared loaf pan and press it down firmly to form an even shape.
Bake for 45 to 50 minutes until the internal temperature reaches 165°F and the top is lightly browned.
Remove from the oven and let the meatloaf rest in the pan for 10 minutes before slicing and serving.