In a medium mixing bowl, whisk together flour, baking powder, soda and salt; set aside. In an electric mixer, beat butter with sugars until light and fluffy. Add egg and vanilla; beat just until well combined. Add dry ingredients; beat on low speed just until flour is no longer visible. Fold in caramel corn and nuts. Drop 20 evenly sized rounded spoonfuls (or use a #40 cookie scoop) 2" apart on 2 parchment-lined baking sheets; flatten slightly with the back of a spoon. Bake pans one at a time in a preheated 325° oven until just barely set and slightly puffy (about 15 min.), rotating pan halfway through. Cool cookies on pans for 2 min.; move to wire racks to cool completely.

Tasty Tip: Make these decadent cookies gift- and holiday party-ready when you drizzle them with a bit of melted chocolate.