Line a large roasting pan with foil and place rack into the pan.
Pat chicken dry with paper towel. Mix chilli sauce with egg yolk. Combine breadcrumbs, parmesan and cayenne in a shallow bowl. Brush chilli sauce mixture over chicken, then coat with crumb mixture, pressing on firmly. Chill for 30 minutes or overnight.
Preheat oven to 220°C. Lay drumsticks onto rack in pan, leaving space between so air can circulate. Spray well with oil. Roast for 40 minutes, turning halfway through cooking, or until chicken is browned and cooked through. Serve with extra chilli sauce, mayonnaise and lemon.