Score the duck skin in a shallow crosshatch pattern, being careful not to cut into the meat.
Season both sides of the duck breasts generously with kosher salt and black pepper.
Place duck breasts skin-side down in a cold pan. Turn heat to medium-low and cook for 10 minutes, allowing the fat to render and skin to crisp.
Remove the duck breasts from the pan and set aside to rest for about 10 minutes while you make the sauce.
Pour off excess duck fat from the pan, leaving about 1 to 2 tablespoons in the skillet.
Add orange juice, orange zest, ginger, chicken broth, white wine, honey, soy sauce, Calabrian chili, and red wine vinegar to the pan.
Simmer over medium heat for 10 to 15 minutes, stirring occasionally, until the sauce reduces and thickens.
Return the duck breasts to the pan, skin side down.
Cook for another 1 to 2 minutes to re-crisp the skin, then flip and sear the flesh side for 30 seconds.
Remove from heat and let the duck rest briefly (no more than 2 minutes).
Whisk the unsalted butter into the sauce until glossy.
Slice duck on a bias and plate with a generous drizzle of the orange glaze.
Garnish with orange slices or zest and fresh herbs. Serve immediately.