Step 1Preheat oven to 180°C. Cook quinoa in a saucepan with 1 cup water over medium heat; bring to the boil. Reduce heat to low, cover and simmer for 12 minutes, or until water has absorbed. Remove from heat and set aside to cool.
Step 2Spray a large non-stick frying pan with olive oil and set over medium heat. Sauté onion until soft. Add garlic, lemon zest and sage; sauté for 1 minute, or until fragrant. Remove from heat.
Step 3Place cooled quinoa, onion mixture, parsley, cranberries and pepitas in a bowl. Stir to combine.
Step 4Place turkey, skin side down, between 2 pieces of baking paper. Pound turkey with a meat mallet until as thin as possible and an even thickness (about 1–2cm). Remove top layer of baking paper and arrange spinach evenly over turkey. Spoon cooled stuffing over the spinach, leaving a 2cm border. Using baking paper to guide you, firmly roll turkey breast to enclose spinach and stuffing. Tie turkey at 2cm intervals with kitchen string. Use toothpicks to secure and tuck in ends of turkey if necessary.
Step 5Put rolled turkey in a roasting tray and pour hot stock in base. Spray turkey lightly with olive oil. Cover entire tray with foil.
Step 6Roast turkey for 30 minutes. Remove foil, then return to oven for a further 20–30 minutes, or until golden brown and juices run clear when a skewer is inserted into the thickest part of the breast. Cover loosely with foil; set aside to rest for 15 minutes.