1.Make herb brine. Add turkey breasts to brine; cover and refrigerate for 3 hours.
2.Pulse olives, butter, breadcrumbs, rind and pine nuts in a small food processor to a coarse mixture. Season with freshly ground black pepper.
3.Remove turkey from brine; pat dry. Discard brine. Using your fingers, carefully loosen skin from flesh of turkey breasts; push olive mixture under skin. Press filling between skin and flesh to spread evenly.
4.Preheat oven to 180°C/350°F. Place a wire rack in a large shallow flameproof roasting pan.
5.Lay half the pancetta slices slightly overlapping on a large piece of plastic wrap on a work bench. Place turkey breast, skin-side down, on pancetta; wrap pancetta around turkey, using plastic wrap to secure. Repeat process with remaining turkey and pancetta.
6.Remove plastic wrap; tie turkey breasts with kitchen string at 2cm (¾in) intervals.
7.Place turkey, skin-side up, on rack in roasting pan. Roast turkey for 1 hour or until internal temperature reaches 74°C/ 165°F on a meat thermometer or when the juices run clear when a skewer is inserted sideways into the thickest part of the breast. Cover loosely with foil if turkey is over-browning.
8.Transfer turkey to a plate; brush pancetta with honey. Cover loosely with foil to keep warm. Stand for 30 minutes. Meanwhile, skim fat from roasting pan. Place pan over medium heat; stir in stock, scraping any browned pieces from base of pan. Simmer for 10 minutes until reduced; transfer to a jug.
9.Slice turkey; serve with gravy.
10.Place 2 cups (500ml) water, wine, sugar, salt, herbs and peppercorns in a medium saucepan. Bring to the boil, stirring, until sugar and salt dissolve. Transfer liquid to a large non-reactive container (6-litre/24-cup capacity); stir in 1 litre (4 cups) water.
Brining helps lean meat such as turkey, chicken and pork to retain moisture as it cooks. You can omit this step if you prefer and simply season the turkey with salt and pepper. Ask your butcher to bone the turkey breasts for you.
do-ahead Recipe can be prepared to the end of step 5, a day ahead and refrigerated; preheat the oven just before cooking.