With the rack in the middle position, preheat the oven to 350°F (180°C). Line a baking sheet with parchment paper or a silicone mat.
Place the popcorn in a large bowl and set aside.
In a small saucepan over medium heat, melt the butter and brown sugar, stirring frequently. Drizzle the hot mixture over the popcorn. With a spatula, toss to coat well. Spread on the prepared baking sheet.
Bake for 5 minutes. Let cool completely on the baking sheet to dry.
The popcorn will keep for 1 week in an airtight container or sealable bag.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.