Turn on the saute function of your pot. Add the ham, and sautee for 2-3 minutes- stirring often. Hit the cancel button, and then sprinkle the ranch powder over top of the ham.
Pour the chicken broth into the pot, followed by the pasta. Using a spatula, push the pasta down into the broth as much as possible, but DO NOT stir.
Add the lid to the pot, turning to close. Turn the vent valve to seal. Pressure cook the pasta according to the time indicated on the box divided in half, and then minus 2 minutes. I cooked mine for 4 minutes for 1 lb of pasta.
Carefully open the valve (avoiding the hot steam spray), and allow the pot to quick release.
When done, open the lid and add the cheeses then stir everything to melt & evenly combine- again carefully to avoid the steam.
The mixture will seem soupy at first. Return the lid to the pot, and let it rest for 5 minutes while the pasta continues to absorb liquid and the sauce thickens.
After 5 minutes, stir again, and then serve.