Identify your sauce thickness: thick/cheesy needs ridges; lighter sauces work well with smooth spirals too.
Choose a 1:1 substitute based on shape: ridged rotini/fusilli for corkscrew grip, ridged elbow/penne/rigatoni for tube-based capture.
Cook until al dente using the package time, then taste 1 minute early—ridged substitutes often finish slightly faster.
Toss immediately with sauce (and a splash of pasta water if needed) to help cling build on the ridges.
If your substitute is smoother than cavatappi, add an extra toss time (30–60 seconds) to improve sauce adhesion.