Bring a large pot of heavily salted water to a boil and cook the pasta according to package directions until al dente.
About 1 minute before the pasta is finished cooking, add the diced broccolini directly into the pasta water to lightly steam and soften.
Before draining, reserve a bit of the pasta water. Drain the pasta and broccolini, then return everything to the pot.
Add the fresh pesto and stir until the pasta is well coated. Add a splash of the reserved pasta water if needed to loosen the sauce and help everything come together smoothly.
Crumble in the feta cheese, then add the diced avocado and toasted pumpkin and sunflower seeds. Gently stir everything together until combined.
Serve warm and finish with salt and pepper if needed, along with a drizzle of fresh balsamic vinegar for that bright, punchy flavour.