Preheat your oven to 400°F (200°C). Line a large rimmed baking sheet with parchment paper.
In a large bowl, combine the ground chicken, breadcrumbs, eggs, Parmesan cheese, minced garlic, fennel seeds, salt, and pepper.
Gently mix the ingredients with your hands until just combined. Be careful not to overwork the mixture.
With damp hands, form the mixture into meatballs about 1.5 inches in diameter (a rounded tablespoon). You should have about 24. Arrange them in a single layer on the prepared baking sheet.
Bake for 20 to 25 minutes, or until the meatballs are browned and cooked through. The internal temperature should read 165°F (74°C) on an instant-read thermometer.
While the meatballs are baking, bring a large pot of salted water to a boil. Cook the pasta according to package directions until al dente.
Before draining the pasta, reserve about 1 cup (240 ml) of the starchy cooking water. Drain the pasta well.
Return the drained pasta to the pot. Add the broccoli pesto and toss to coat, adding the reserved pasta water a tablespoon at a time until the sauce reaches your desired consistency. You can also add a drizzle of olive oil if needed.
Divide the pasta among serving bowls and top with the baked chicken meatballs. Serve immediately with extra grated Parmesan cheese.