1. PREHEAT oven to 350°F.
2. Spray a 9”x13” baking pan with baking oil.
3. Whisk together all-purpose flour, cinnamon, ginger, baking soda, salt, allspice, nutmeg and cloves (if using; set aside.
4. Using an electric mixer, beat butter and dark brown sugar about 4 minutes, or until light and fluffy. Add egg and vanilla extract and beat until blended. Add flour mixture in two additions alternating with the pumpkin; beating until just combined after each addition. Stir in raisins and chopped walnuts. Spread batter into prepared pan.
5. Bake until a cake tester inserted into center comes out clean, about 25 to 30 minutes. Cool completely on wire rack.