Preheat oven to 300º F. Melt butter and toss with pumpkin seeds in a bowl. Add a generous pinch of kosher salt and freshly ground black pepper. Spread out on a baking sheet lined with foil (for easy cleanup).

Roast pumpkin seeds about 40 minutes, moving/flipping with a spatula once. Remove from the oven and use foil to lift the seeds and place into a bowl. Add a few drops of truffle oil (4-8 will do the trick) and toss. Start with a lesser amount and gradually add more to get the right taste. Serve immediately.