In a microwave-safe bowl, melt butter and chocolate. Stir until completely smooth. Cool for 5 minutes. Whisk in the sugars, egg and vanilla.
In a separate bowl, combine the flour, malted milk powder, cocoa, baking powder and salt. Add to chocolate mixture and mix until combined. Stir in milk chocolate chips and malt balls. Use a medium-sized cookie scoop to form 16 cookies.
Bake at 350°F for 8-10 minutes or until set. Cool for 5 minutes before removing to a wire rack to cool completely.