I know you'd expect me to talk about the flour, or eggs verses egg yolks. However while the type of flour may makes a small difference and extra egg yolks add richness, this tagliatelle recipe is the one I grew up on. My family didn't have access to special flour - we just used ordinary plain or all purpose flour. And the eggs from our chickens were rich and yellow. Naturally, the better your ingredients, the better the result. See the notes section in the recipe for further tips.