Pop your corn using an air popper or the stove. Place the fluffy popcorn into a very large bowl. Make sure to pick out any hard, unpopped seeds. You don’t want anyone to hurt a tooth while snacking!

Line a large cookie sheet with parchment paper. This prevents the sticky toffee from gluing to the metal. You can also use a silicone baking mat if you have one. Set this aside for later.

Put the butter, white sugar, and brown sugar in a saucepan. Add the corn syrup and the salt. Turn the heat to medium. Stir gently until the butter melts and the sugar dissolves completely.

Bring the mixture to a steady boil. Stop stirring once it starts bubbling. Let it cook for about 5 to 7 minutes. It should turn a beautiful golden-brown color like a shiny penny.

Remove the pan from the heat immediately. Stir in the vanilla extract and the baking soda. The mixture will bubble up and get very foamy. This creates a light, airy texture for the toffee.

Pour the hot toffee over the popcorn in the bowl. Use a large spoon to toss everything together. Try to coat every single piece of popcorn. Work quickly before the sugar starts to harden.

Spread the coated popcorn onto your prepared baking sheet. Put it in an oven preheated to 250°F (120°C). Bake for about 40 minutes. Stir the popcorn every 10 or 15 minutes.

Take the tray out of the oven. Let the popcorn cool completely on the counter. Once it is cold, it will be very crunchy. Break the large clumps apart with your hands.