Chocolate chip cookies don’t have to be limited simply to a cookie shape. These bars cut easily and are a perfect addition to a cookie tin mix.
Preheat the oven to 350ºF and line an 8-inch square baking pan with parchment paper, so that the paper comes up the sides.
Beat the butter and cream cheese and beat in the brown sugar. Add the egg and vanilla and beat well.
In a separate bowl, sift the flour, salt and baking powder. Stir this into the butter mixture until evenly blended and then stir in the chocolate chips. Spread this into the prepared pan and baked for 30 to 35 minutes, until the edges have browned slightly (the top will remain light). Cool this completely in the pan before frosting.
For the frosting, beat the butter and peanut butter until smooth and then beat in the icing sugar, vanilla and salt until smooth. Spread this over the top of the cooled bars and chill for at least 2 hours before slicing into 36 squares.
The bars will keep up to a week, refrigerated, or can be frozen for up to 3 months.