Preheat the oven to 325 degrees F. Line a 9-by-13-inch pan with parchment paper.
Cream together the brown sugar, butter and granulated sugar in the bowl of a stand mixer on medium speed until light and fluffy, approximately 3 minutes Add the eggs 1 at a time, beating for 1 minute after each addition. Add the malted milk powder and vanilla. Reduce the mixer speed to low and add the flour, baking powder, baking soda and salt, mixing until just incorporated. Mix in the toffee bits, chopped pecans, chocolate chips and malted milk balls.
Transfer the batter to the prepared pan. Top with the chopped pretzels, patting them into the batter. Bake until golden on top and a toothpick comes out clean with a couple fudgy crumbs, 35 to 40 minutes. Let cool completely before cutting.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.