Heat a pressure cooker over medium flame and melt the butter with the refined oil. Add the unpopped popcorn kernels and cover with the lid, leaving a slight gap for steam to escape. Cook while shaking the cooker occasionally to prevent burning, and continue until the popping sound subsides. Remove from heat once the popping has stopped.

Transfer the freshly popped corn into a large mixing bowl. Season with salt and black pepper, then sprinkle in the garlic salt and oregano. Toss thoroughly to coat the popcorn evenly with the seasonings.

Add the grated cheddar cheese and mix once more so it melts slightly and clings to the warm popcorn. For an extra cheesy finish, sprinkle a little more cheese on top before serving. Enjoy the popcorn warm for the best flavor and texture.