In a large skillet, heat 1 1/2 tablespoons of the olive oil over medium high. While the oil heats, combine the chili powder, cumin, kosher salt, and cayenne pepper in a small bowl. Once the oil is hot and shiny, add the zucchini rounds in a single layer, then sprinkle with half the spice mixture. Let cook until the first side is golden, about 4 minutes, then flip, sprinkle with the remaining spice mixture, and cook on the other side until it is golden as well, 3-4 additional minutes. Remove to a plate and cover to keep warm.