In a large bowl, combine brown sugar and white sugar. Heat butter in a medium saucepan until brown and add sugar. Leave aside and allow the mixture to cool for about 10 minutes.
In a small bowl, stir together the flour, baking powder, baking soda and salt. After the butter has cooled, add the peanut butter and honey. Beat with a mixer on medium speed until smooth.
Add egg and beat. Then whisk with milk. Add flour mixture and stir until smooth.
Cover the dough and refrigerate for at least 2 hours or overnight. Preheat oven to 175 degrees. Line a baking sheet with parchment paper or a silicone mat. Form the dough into small 2.5 cm balls.
Press down on the balls with a fork, holding it first in one direction and then in a perpendicular direction so that the cookie is covered with a grid. Bake the cookies in the oven until they start to darken around the edges, about 9-10 minutes.
Remove the cookies from the oven, sprinkle with sugar and allow to cool on a baking sheet, then allow to cool completely on a wire rack.