In a pot, boil water and season with salt. Add in the dried pasta and cook until done.
In the meantime, to make your sauce, in a large skillet over medium high heat, add the pesto and heavy cream. Stir together until well combined then add in the mascarpone cheese. Stir until well combined and the cheese has melted. Add in the red pepper flakes, salt (to taste) and let sauce simmer over low heat for 15 minutes, or until sauce has thickened. If sauce gets too thick, use some of the pasta water to thin it out.
When pasta is done, add to the sauce and stir to combine, coating every strand.
Serve with fresh parsley on top.
Notes
You can add a protein to this such as chicken. It'd be a great addition :)