Step 1

Preheat your oven to 200°F and line two large rimmed baking sheets with parchment paper.

Step 2

Heat the vegetable oil in a very large pot over medium-high heat. Add the popcorn and shake the pan to coat the kernels with oil. Cover with a tight fitting lid (alternatively, cover tightly with foil). Wait for the popcorn to start popping, then shake the pan gently every now and again to keep the kernels moving. When the popping slows to about 2 seconds apart, remove the pan from the heat. Transfer the popcorn to a large bowl, making sure to leave any unpopped kernels behind.

Step 3

In a medium saucepan over medium heat, melt the butter. Add the brown sugar, corn syrup, maple syrup and salt and stir until the sugar dissolves. Let the mixture come to a gentle boil. Stirring occasionally, boil the syrup over medium heat for 5 minutes. Remove the pan from the heat and add the baking soda. Stir well as the mixture turns foamy.

Step 4

Immediately and carefully (it's very hot!) pour the syrup over the popped corn in three separate additions, stirring gently as you go, until the popcorn is evenly coated. (If at any point the caramel stiffens and becomes difficult to pour, you can rewarm it gently on the stove.)

Step 5

Spread the caramel corn into even layers on prepared pans. Bake at 200°F for one hour. The caramel will be a little soft at this point; let it cool completely to crisp up. Store in an airtight container for up to 4 days.

Step 6

Note: If you want to use microwave (be sure it's plain) or air-popped popcorn, note that ⅔ cup popcorn kernels makes 16 cups.