Preheat oven to 350°F. Line a 9x9” pan with foil and spray liberally with cooking spray so that the bars don’t stick.
Add cake mix, butter, egg, milk, and 1/4 cup Ovaltine to the bowl of an electric mixer fitted with a paddle attachment. Mix until a thick dough forms. Note: you can do this with a hand mixer but it will take a long time for the dough to come together, so just be prepared.
Press about 1/2 of the dough into the bottom of the prepared pan. Stir 3 tablespoons of Ovaltine into the sweetened condensed milk and pour over the top of the base. Sprinkle 1 cup of the crushed malted candy over the top.
Separate remaining dough into small balls and evenly space over the top of the bars. Press down to flatten. Sprinkle with the remaining 1/4 cup of malted candy and press lightly to stick.
Bake bars for about 25-30 minutes, or until they just begin to brown. Cool completely before slicing, otherwise the mixture will be too gooey to cut. Optional: eat straight from pan with a fork.