1/2 cup creamy or crunchy peanut butter
1/4 cup butter, softened (1/2 stick)
1 cup firmly packed light brown sugar
1 teaspoon vanilla extract
1 cup self-rising flour
1 cup semisweet chocolate chips (6 ounces)
Preheat the oven to 300 degrees F.
Coat an 8-inch square baking pan with nonstick cooking spray.
In a medium bowl, with an electric beater on medium speed, beat the peanut butter, butter, and brown sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Blend in the vanilla extract, then beat in the flour. Fold in the chocolate chips until well combined, then spread evenly in the baking pan.
Bake for 45 to 50 minutes, or until golden. Remove from the oven and place the pan on a wire rack. Allow to cool completely before cutting.