1. Adjust 2 oven racks to upper and lower positions; preheat oven to 325°. Line 2 rimmed baking pans with parchment paper. In medium bowl, whisk flour, cornstarch, baking powder, baking soda and salt. In large bowl, with mixer on medium speed, beat sugar and butter 2 minutes or until light and fluffy, scraping bowl occasionally with rubber spatula. Add egg, peanut butter and vanilla extract; beat 2 minutes or until well combined. Scrape down bowl; reduce speed to low. Gradually add flour mixture, beating 1 minute or until well combined. Stir in oats, chocolate chips and candies. Makes about 4 cups dough.
2. Using 2 spoons, drop about 1/4 cup dough, 2 inches apart, on prepared baking pans; press with back of spoon to flatten and bake 18 minutes or until edges of cookies are golden brown, turning pans and rotating pans between upper and lower racks halfway through baking. Cool cookies on pans 1 minute, then transfer to wire rack to cool completely. Makes about 16 cookies.

Approximate nutritional values per serving (1 cookie): 275 Calories, 15g Fat, 7g Saturated Fat, 28mg Cholesterol, 76mg Sodium, 34g Carbohydrates, 2g Fiber, 20g Sugars, 14g Added Sugars, 5g Protein