Coat bottom and sides of 9 x 13 inch ovenproof glass baking dish with vegetable spray. if using metal baking pan, line it with foil, shiny side up, and coat with vegetable spray. Rinse chicken under cold running water and pay dry with paper towels. Put lemon juice in shallow bowl. Dip chicken in lemon juice, put on platter and set aside. Pour leftover lemon juice into prepared pan.
Put flour, salt and paprika in plastic bag. Add chicken, seal and shake to coat with flour. Put chicken in strainer and tap over sink to remove excess flour. Set aside.
Set oven rack in middle position. Preheat oven to 375.
Melt olive oil and butter in large skillet over medium heat. Add chicken and cook til both sides are golden brown. Remove chicken to prepared baking pan and scatter lemon slices over. Sprinkle with brown sugar.
Pour chicken stock into skillet set over medium heat and simmer, scraping with wooden spoon to retrieve all of the browned bits clinging to bottom of pan. Cook til slightly thickened. Pour sauce into a corner of the baking pan, being careful not to disrupt the lemon slices and brown sugar topping. Gently shake pan to distribute sauce over bottom. Cover pan with foil and bake til chicken is cooked through, about 30 minutes for boneless skinless chicken breasts, 40 to 45 minutes for bone in pieces or chicken. Baste with pan juices at least once during cooking. Serve lemon chicken on a bed of saffron rice with pine nuts and golden raisins if desired.