Herb Roasted Turkey Breast with Pan Gravy

small (golf-ball sized) onion, peeled and coarsely chopped

lemon, scrubbed clean

fresh sage leaves

Large handful fresh flat-leaf parsley (about 1/2 cup, from 12 stems)

extra-virgin olive oil, plus more for oiling pan

salt, plus more as needed

fresh bay leaves

butter

boneless turkey breast halves, skin on (about 2 to 2 1/2 pounds each)

Freshly ground black pepper

all-purpose flour

apple or regular brandy (recommended: Calvados)

to 3 cups apple cider

Salt and pepper