Immediately drizzle hot mixture over popcorn and nuts, trying to cover as many kernels as possible. Quickly toss to coat with syrup. Important Note: Syrup will harden quickly, and may not cover all kernels. So return the baking sheet with popcorn mixture to a 350-degree oven. Every five minutes or so, toss the popcorn mixture with spatula until all kernels are covered. (It may take 2-3 times to completely coat each kernel without leaving pools of sugar mixture on baking sheet.)