Preheat the oven to 200ºF (95Cº). Line a large baking sheet with nonstick parchment paper or a silicone mat, such as a silpat.* Place the popcorn in an extra-large lightly greased bowl. Wipe out any excess oil or grease with a paper towel.
In a medium-size, heavy bottom saucepan over medium heat, melt the butter, brown sugar, honey, corn syrup and salt together, stirring gently. When the mixture comes to a boil, stop stirring and let the mixture bubble for 5 minutes. Stir in the vanilla and baking soda. The mixture will foam up. Remove from heat.
Carefully pour half of the caramel mixture over the popcorn. Stir gently, then pour the remaining caramel over the popcorn. Stir again. Add the almonds, then stir once more. Transfer the caramel popcorn to the baking sheet, arranging it in an even layer. Bake for about 1 hour, stirring gently every 15 minutes. Remove from the oven and let cool completely. Sprinkle with sea salt to taste if desired.
Recipe Notes
To find my favorite large baking sheets, click here.