Bring a large pot of water to a boil for the pasta. Once boiling, add the pasta and continue to boil until the pasta is tender (about 7-10 minutes).
When the pasta is just tender, add the frozen broccoli florets to the boiling water with the pasta, and let it sit for about one minute. Reserve a ¼ cup of the starchy pasta water, then drain the pasta and broccoli in a colander.
Return the drained pasta and broccoli to the pot with the burner turned off. Add the butter and ranch seasoning and stir until the butter is melted and everything is coated in the seasoning. If the pasta becomes dry while stirring, add a splash of the reserved pasta water.
Finally, season the pasta with salt and pepper to taste. Serve warm.