Preheat oven to 350°F. Process Rice Chex in a food processor until finely ground into crumbs. Mix the cereal crumbs with melted butter and sugar until well combined.
Press the Chex mixture firmly into the bottom and up the sides of a 9-inch pie pan. Bake the crust for 8 minutes, then remove and set aside.
In a large bowl, whisk together the pumpkin puree, sweetened condensed milk, eggs, cinnamon, ginger, nutmeg, and salt until smooth and well combined.
Pour the pumpkin filling into the prepared crust and smooth the top with a spatula.
Bake for 45-50 minutes until the center is just set but still has a slight jiggle. Cool completely on a wire rack, then refrigerate for at least 3 hours before serving.