Preheat oven to 350°F. Line 13 x 9-inch pan with parchment paper or foil, leaving a 1-inch overhang. Spray with cooking spray and set aside.
Combine oil, sugar, eggs and vanilla in mixing bowl; stir well. Combine flour, baking powder and salt in bowl, stirring to blend. Add to oil mixture and stir until well mixed. Fold in chocolate chips, cherries and walnuts. Transfer to prepared pan.
Bake for 40 to 45 minutes or until light brown and firm in center. Remove from oven and cool in baking pan. Cool completely prior to cutting. To cut, transfer from baking pan to a cutting board and cut into bars.
Optional: Garnish bars with a drizzle of melted chocolate. Place 1 cup dark chocolate chips in a microwave-safe bowl. Heat 1/4 cup cream or milk to boiling; pour over chips and let stand 2 minutes. Microwave on 50% powder for 20 seconds at a time if needed to completely melt. Stir until very smooth. Drizzle over bars with a spoon. OR, transfer to a resealable plastic bag. Snip a tiny corner and squeeze chocolate over bars.