Add in the flour and cook for 3-5 minutes mixing every 10-20 seconds to ensure the flour doesn't burn. Flour will make a thin, loose paste.
Add the broth and cook until it starts to thicken, approx. 1-2 minutes.
Add 1/2 cup of pasta water and cook for 3-4 minutes allowing the sauce to come to a simmer. If the sauce thickens too much feel free to add more pasta water 1 tbsp at a time. Salt to taste depending on how salty the pasta water was.
TURN OFF THE HEAT, and allow the sauce to stop bubbling. Let the sauce cool for 2-3 minutes before adding in the Franks hot sauce.
Add in the Boursin, crushing it with the back of a spoon and mixing to combine. This will take a minute or two for the cheese to completely melt into the sauce.
Add in the pasta and mix to coat. Serve immediately.
Notes
While there is no chicken added directly to this buffalo chicken pasta, optional to add in sliced grilled chicken breast or shredded rotisserie chicken.
To make melting the Boursin a little easier take it out of the fridge at minimum in the beginning of cooking, recommended 10-15 minutes before.