Gather all your ingredients: popcorn kernels, butter, garlic, rosemary, and Parmesan cheese.
Heat the canola oil in a large pot over medium heat. Add a few popcorn kernels and cover. Wait for them to pop to indicate the oil is ready, then add the remaining kernels in an even layer and cover again.
Shake the pot gently back and forth over the heat to prevent burning and ensure even popping. Keep shaking until popping slows to about 2 seconds between pops.
While the popcorn pops, melt the butter in a small saucepan over low heat. Add the minced garlic and rosemary, allowing to infuse for about 1-2 minutes without browning the garlic.
Once popped, pour the popcorn into a large mixing bowl. Drizzle the garlic rosemary butter over the popcorn, tossing gently to coat.
Sprinkle the freshly grated Parmesan cheese over the popcorn while tossing to distribute evenly. Add salt to taste and mix well.
Transfer the popcorn to a serving bowl or individual bags and enjoy warm!