Step 1 : Melt butter in heavy saucepan over medium-low heat, then add both sugars. Stir constantly until the sugar begins to dissolve, then lower the heat. Stir occasionally until the mixture is completely liquid and starts to turn a light brown.

Step 2 : Add the salt, cinnamon, and vanilla and stir to combine.

Step 3 : Place the apple slices in the caramel mixture, cooking until soft.

Step 4 : Remove the apples and eat them while you prepare the popcorn.In a large pot with a lid, heat the oil over medium-high heat. Test the temperature by throwing in one kernel--if it pops, the oil is hot enough for the rest of the kernels.

Step 5 : Add the kernels and shake once to coat with oil, then cover the pot with the lid. Once the popping has slowed, turn off the heat and set the pot aside.

Step 6 : Pour the reserved caramel into the pot with the popcorn, cover with a lid, and shake to coat. Enjoy!