Preheat oven to 350 F. Line a large baking sheet with a Silpat baking mat or parchment paper and set aside.
In a large bowl, whisk flour, malted milk powder, cornstarch, baking soda and sea salt together. Set aside.
In the bowl of a stand mixer, cream together butter and sugars until smooth and creamy, about 3 minutes. Add egg and vanilla extract and beat until combined. Slowly mix in the dry ingredients.
Stir in the chocolate chips and malted milk balls. Form cookie dough into tablespoon balls and place on prepared baking sheet, about 2 inches apart.
Bake cookies for 10 minutes, or until slightly golden brown around the edges. Let the cookies cool on the baking sheet for two minutes. Transfer to a wire cooling rack and cool completely.
Note-you can find malted milk powder at most grocery stores by the chocolate milk and instant breakfast powders.