Pour unpopped popcorn into brown paper bag and fold top of bag over three times. Lay bag seam side down (so that the folds don't reopen during popping) in microwave. Microwave for about 1:45 to 2 minutes, or on your microwave's popcorn setting, if it's reliable.
Pour popped popcorn into a bowl and separate out any unpopped kernels.
Melt white chocolate chips in microwave for about 2 minutes, stirring every 30 seconds.
Drizzle half of the melted chocolate over the popcorn. Carefully stir. Drizzle the rest of the chocolate over popcorn and stir again. Fold in crushed peppermint.
Spread popcorn out on parchment paper or greased foil, sprinkle with sea salt, and allow to sit until set. I put mine in the refrigerator for about 45 minutes.
Break popcorn apart and store in bags or an airtight container.