additional chopped malt balls to sprinkle on top(optional)
Preheat oven to 375°F.
In a large bowl, use an electric mixer to beat the butter for about 30 seconds. Add the sugars and baking soda and beat until combined. Beat in the eggs, vanilla and melted chocolate. Beat in as much of the flour as you can with the mixer. Stir in any remaining flour and the malted milk powder. Stir in the chopped malted milk balls.
Drop the dough from rounded teaspoons 2½ inches apart onto an ungreased cookie sheet. Add additional chopped malt balls on top, if desired (the baked cookie will be prettier). Bake about 10 minutes or until the edges are firm. Cool on a cookie sheet for 1 minute. Transfer cookies to wire racks; cool.
Look for malted milk powder in the baking aisle of your local market-- or sometimes it can be found near the hot chocolate/coffee.
To store, place in airtight container and cover- store at room temperature for up to 3 days. Or freeze for up to 3 months.