For topping: Grind buttermilk powder, garlic powder, onion powder, salt, and pepper in spice grinder to fine powder. Add chives and pulse until finely chopped, about 3 pulses.

Set wire rack in rimmed baking sheet and line with double layer of paper towels. Heat oil in large Dutch oven over medium heat to 375 degrees. While oil heats, slice potatoes crosswise 1/16 inch (1½ millimeters) thick. Carefully add all potatoes to oil, 1 small handful at a time, separating slices as much as possible (oil will bubble vigorously). Cook, stirring constantly with wooden spoon, until bubbling has calmed (it will not completely stop) and slices begin to stiffen, 2 to 4 minutes.

Continue to cook, stirring frequently, until shape of chips is set and slices are rigid at edges (chips will make rustling sound when stirred), about 5 minutes longer, adjusting heat as needed to maintain oil temperature between 240 and 250 degrees.

Continue to cook, stirring and flipping potatoes frequently with spider skimmer or slotted spoon, until all bubbling ceases and chips are crisp and lightly browned, 6 to 8 minutes longer, adjusting heat as needed during final minutes of cooking to maintain oil temperature between 280 and 300 degrees. Using spider skimmer or slotted spoon, transfer chips to prepared rack. Let chips cool for 30 seconds, then transfer chips to large bowl with topping and toss until evenly coated. Serve. (Chips can be stored in zipper-lock bag at room temperature for up to 5 days.)