1Heat the oven to 425°F with a rack in the upper third. Set a wire rack on a rimmed baking sheet.
2Spread the frozen popcorn chicken in a single layer on the rack, with space between the pieces so hot air can reach all sides. Bake straight from frozen for 18 to 22 minutes, flipping once halfway through, until deep golden and crisp.
3While the chicken bakes, make the glaze. In a small saucepan combine the gochujang, soy sauce, honey, brown sugar, rice vinegar, garlic, ginger, and gochugaru if using. Simmer over medium-low heat 3 to 4 minutes, stirring, until syrupy and fragrant. Take off the heat and stir in the sesame oil.
4Toss the hot chicken in a large bowl with the warm glaze until evenly coated. Work quickly and gently so the breading stays crisp.
5Pile onto a platter and finish with the sesame seeds and scallions. Serve right away. The crust will be crunchy rather than glass-crackly like double-fried wings, and there is no frying oil to strain or dispose of.