Frito Pie is one of those "poor white trash" comfort foods which is fattening as hell, but completely irreplacable. When the craving hits, there's just no substitute.
Here's how you make it:
Serve and eat immediately, or the Fritos will get soggy. Alternatively, serve the ingredients separately and allow folks to ladel it into their bowls. This allows people to fiddle with the ratios to suit their tastes, and also make it in small batches to be eaten as needed (which neatly avoids the problem of Frito sogginess).
Frito Pie Los Angeles:
As above, but hold the cheese, and put the Fritos on top of the chili, instead of visa-versa.
Note: A distant cousin of Frito Pie which is very healthy is Primordial Soup (qv).