Drizzle basil infused oil over the popcorn. Grind grey salt in a spice grinder (a coffee grinder also works well for this purpose) until fine ¿ it will stick to the popcorn more evenly if the crystals are smaller. Add black pepper, then grate parmesan over the popcorn.;
Preheat a large cast iron Dutch oven on a stovetop over high heat. Add olive oil, then popcorn. As soon as it begins to pop, cover and turn down to medium heat until sound of popping stops, about 3 to 4 minutes.