Preheat oven to 350 and line a cookie sheet with parchment. In a medium bowl, using a handheld mixer, beat together butter and peanut butter until uniform in color. Add sugar, and beat until fluffy. Add the egg and beat until combined, about 1 minute.
In a small bowl, whisk together flour, salt, baking soda, and baking powder. Add flour mixture to peanut butter mixture and beat until just combined.
Drop rounded tablespoons of batter onto the cookie sheet and bake for 8-12 minutes, depending on your doneness preference. I like them at 8.
Meanwhile, place raspberries and a tablespoon of white sugar in a food processor and puree. Pour pureed raspberries through a fine mesh sieve over a small bowl and press with a spatula to extract juice from the pulpy mixture. Discard the seeds. Whisk confectioners sugar into raspberry juice until thick enough to drizzle over cookies. I used 1/2 cup.
Allow cookies to cool completely. Using a spoon, drizzle raspberry glaze over cookies and serve with a cold glass of milk.