Preheat oven to 350. Butter a 8x8 baking pan and set aside.

In a medium bowl, whisk together the dry ingredients. Set aside.

In the bowl of a standing mixer, or in a large bowl with a hand-held mixer, cream together butter and peanut butter until smooth.

Add in the sugars and mix until well combined..

Add egg, vanilla and milk and beat until until the mixture is smooth, about a minute.

While the mixer is running, stream in the dry ingredients and mix until combined.

Press the dough evenly into the prepared baking pan,

Bake 22-25 minutes until the top is lightly browned and they look set.

Place the Hershey Kisses on the bars, spaced evenly.

Return to the oven for 2 minutes.

Cool, in pan, on wire rack.

Cut into squares and store in an air-tight container at room temperature up to 3 days. The bars also freeze well.