Preheat over to 300° and prepare a cookie sheet with parchment paper.
First, you'll want to beat your egg white until frothy (takes one or two minutes). Pour enough egg white over your cashews until they are fully coated (you may not need the whole thing) and stir.
Add your brown and white sugar, cinnamon, and salt to a bowl, and stir to combine. Pour the sugar mixture over your nuts and stir until coated.
Spread the nuts out onto the baking sheet (try to get them in a single layer and not stacked on each other) and bake for 25-30 minutes (stir halfway through). They may look a little wet still when you take them out, but they will crisp up as they cool. Let them sit for at least 30 minutes before eating.
Break up nut clusters and store leftovers in an airtight container.