Preheat oven to 350 degrees Fahrenheit and grease an 8" baking pan.

Combine the peanut butter, butter, brown sugar and sugar in a large bowl and mix until well blended.

Add in the egg, milk and vanilla and beat until blended.

In a separate bowl, combine the flour, baking soda and salt and mix well.

Add the flour mixture to the peanut butter mixture and beat until blended.

Spread half of the batter in the bottom of the prepared pan.

Chop 9 Reese's into bite size pieces and distribute evenly over the batter.

Using a spoon, drop the remaining batter on top of peanut butter cup pieces.

Bake for 30 minutes or until browned.

Chop 3 more Reese's into pieces and press lightly into the top of the bars while still warm.

Cool completely before cutting.