Cook the pasta

• Bring salted water to a boil in a stockpot.
• Cook the pasta until al dente, then drain, keeping a dash of pasta water.

Make the roux

• Melt the butter in a pan over medium heat.
• Add the flour and mix to combine.

Build the sauce

• Add the tomato paste and let it cook for a few minutes.
• Pour in the heavy cream, whisking constantly to avoid lumps.

Finish and serve

• Add the parmesan cheese and stir until melted.
• Add the cooked pasta with a dash of pasta water and toss to coat.