Heat the Oil and Test Kernels: Place a large, heavy-bottomed stockpot or Dutch oven over high heat. Pour in the coconut oil and add three popcorn kernels to the pot. Cover with a lid and wait for these “test kernels” to pop, which signals that the oil has reached the perfect temperature for popping.
Prepare the Butter and Seasoning: While waiting, melt the butter gently—either in a microwave-safe bowl in short 30-second bursts or on the stovetop in a small pan. In a separate small bowl, combine the grated Parmesan, garlic powder, and red pepper flakes, mixing well to create a flavorful seasoning blend.
Pop the Popcorn Kernels: Once the test kernels have popped, remove the pot from the heat and immediately pour in the remaining 1/2 cup of popcorn kernels. Cover and gently swirl the pot side to side for about 20 seconds to coat the kernels evenly with hot oil. Return the pot to the heat, cover again, and the kernels will begin popping rapidly.
Control Steam and Finish Popping: When the popping slows down and the pot is roughly half full of popcorn (about 30 seconds to 1 minute in), slightly lift the lid to allow steam to escape. This step helps keep the popcorn crisp. If some kernels haven’t popped, gently shake the pot to encourage even popping. When popping nearly ceases, remove the pot from heat immediately.
Season and Serve: Transfer the freshly popped popcorn to a large mixing bowl. Drizzle with the melted butter and toss thoroughly to coat every kernel. Sprinkle the Parmesan-garlic-pepper mixture evenly over the popcorn and toss again until well combined. Add fine sea salt according to your taste preference and serve immediately for best texture and flavor.