Ingredients

• 3/4 cup (1 1/2 sticks) butter
• 3/4 cup granulated sugar
• 3/4 cup packed light brown sugar
• 3 eggs
• 1 teaspoon vanilla extract
• 2 cups all-purpose flour
• 2 teaspoons baking powder
• 1/4 teaspoon salt
• 2 cups (12 oz.) semi-sweet chocolate chips
• 1/2 cup chocolate syrup
• 1/2 cup chopped nuts (optional)

Directions

Preheat oven to 350° F. Grease a 13-x-9-x2-inch baking pan (spread with butter or spray with nonstick cooking spray).

Add butter, granulated sugar and brown sugar to an electric mixer bowl and beat on medium speed until well-blended, stopping once during mixing to scrape sides and bottom of bowl to incorporate all ingredients.. Add eggs and vanilla and beat just until well-blended.

In a separate mixing bowl, whisk together flour, baking powder and salt. Add to the butter, sugar and egg mixture and mix on low speed until well-blended and smooth, stopping once during mixing to scrape sides and bottom of bowl to incorporate all ingredients. Remove bowl from electric mixer and manually stir in chocolate chips (and nuts, if using).

Divide the batter into 2 equal portions (each portion should measure to about 2 1/2 cups). Evenly spread one of the batter portions into the greased baking dish. Spoon chocolate syrup over the center of the top of the batter, while not allowing chocolate to spread to the sides of the baking pan. Evenly spread the chocolate syrup over the surface to within 1/2 inch of the edges (this will help to prevent the chocolte syrup from oozing out of the sides while baking). Drop teaspoonfuls of the remaining batter over the syrup to almost completely cover the surface. (Don't worry about the spaces in between the pieces of batter, as this might help to create a paisley effect during baking.)

Bake for 30 minutes, or until top has lightly browned and a toothpick inserted into center comes out clean. Cool completely in the pan on a wire rack, then cut into bars.