1.   At the very end, gently swirl in a heart-clogging hunk of butter until the sauce becomes a creamy emulsion.

2.   Before hot sauce became a national obsession, anyone who used it did so not only for the heat but also for the taste.

3.   Add broth from the original saucepan, and cook and stir over medium heat until sauce becomes semiclear and thick.

4.   Add more pasta water, if sauce becomes too dry.

5.   Bring to a boil, stirring constantly, until sauce becomes thick.

6.   If the sauce has become very thick, thin it with a few tablespoons of the pasta-cooking water.

7.   If the sauce becomes too thick to beat before all the butter is added, beat in a little of the lemon juice.

8.   If the sauce becomes too thick, add water to thin it.

9.   If sauce becomes too thick, add a little cooking water.

10.   If sauce becomes too thick while baking, add a little water to pan to thin.