Heat a large heavy pot over high heat and add the beef, breaking it up into small pieces and seasoning with salt and pepper; cook until browned and cooked through (4-5 minutes)
Push the beef to one side and add the onion and carrots to the rendered fat, season, and cook until the onion is translucent (5 minutes)
Stir in the red curry paste and cook until darkened and fragrant
Add the tomato sauce, swishing a bit of water in the can to get it all into the pot
Bring to a simmer, reduce heat, and let it cook while the pasta boils until al dente
Reserve ½ cup of the pasta water, then add the drained pasta to the sauce
Stir in the heavy cream and season to taste
Loosen with pasta water if needed before serving hot
