1 bag microwave popcorn, such as Newman's Own Natural
4 tablespoons (1/2 stick) unsalted butter, melted
1/2 cup finely grated Italian Parmesan cheese
1/2 teaspoon chipotle chile powder
2 teaspoons fleur de sel
Microwave the popcorn for 3 to 5 minutes, according to the directions on the package, until the popcorn stops popping. Carefully pour the hot popcorn into a large bowl and immediately pour on the butter, then the Parmesan, chile powder, and salt. Toss well and serve hot.