Preheat the oven to 300 degrees.
Measure the pecans and almonds onto the baking sheet. Roast in the oven at 300 degrees for 5 to 10 minutes. Remove and set aside.
Pop the corn. I use my air popper. You may use any method. It takes me 2 batches of air-popped corn to get 10-12 cups popcorn. Place the popped corn and nuts in your largest bowl. Set aside.
In a heavy 2 quart saucepan over low to medium heat add the butter, sugar, corn syrup and cream of tarter. Stir with a wooden spoon until the mixture reaches 240 degrees- soft ball stage, about 10-15 minutes. Use your candy thermometer to check the temperature from time to time or leave your thermometer in the pan as you stir. Remove from heat.
Add baking soda and vanilla- which will foam up a little. Stir. Pour the hot mixture over top the popcorn and nuts and mix thoroughly. Salt as desired.
Lightly spray a large baking sheet with oil. Pour the caramel popcorn on and spread it out to cool. Store in plastic bags. Enjoy!!