Preheat the oven to 350ºF and line a baking sheet with parchment paper.
In a large heavy-based pot, melt 2 tablespoons of butter over MEDIUM heat. Place 2 popcorn kernels in the melted butter. Cover with the lid and let the two kernels pop.
Pour in the rest of the kernels and shake the pot to form a single layer. Replace the lid and keep on the heat. Once the popping starts, crack the lid a little to let the steam out.
When there is frequent popping, turn down the heat for a few minutes. Once the popping has subsided, remove the pot from the heat.