Season the chicken: In a small bowl, mix the kosher salt and baking powder. Season the chicken legs generously all over and let sit at room temperature for about 10 minutes.

Preheat the oven to 425°F.

Heat a large skillet over medium-high heat. Add the butter and oil. Sear the chicken skin-side down, working two pieces at a time, until deeply golden and crisp, about 3 minutes. Flip and cook for 2 minutes more. Transfer to a baking sheet and repeat with remaining legs.

Roast the chicken for 20 minutes, until cooked through.

While the chicken roasts, return the skillet to medium-low heat. Add the shallots and remaining butter and cook until soft and translucent, about 5 minutes.

Sprinkle in the flour and cook, stirring constantly, until sandy and lightly toasted, 2–3 minutes.

Remove the chicken from the oven and transfer the legs off the baking sheet. Carefully deglaze the hot sheet pan with the sherry vinegar, scraping up any browned bits. Pour everything into the skillet.

Add the honey, then slowly whisk in the chicken stock. Simmer until the sauce is glossy and thickened to your liking. Season with salt and pepper.

Remove from heat and fold in the chives.

Spoon the sauce onto plates and nestle the chicken on top so the skin stays crisp.