Spray x-large roasting pan with cooking spray. Mix together popcorn and peanuts on pan. Place in 250°F oven while preparing caramel glaze.
In a heavy bottomed 2-quart saucepan. combine brown sugar, corn syrup, butter and salt.
Stirring constantly, bring to a boil over medium heat. Lower the heat to medium-low boiling or 5 minutes WITHOUT STIRRING.
Remove from heat. Stir in baking soda and vanilla and mix well. (Mixture will foam) Pour syrup over warm popcorn mixture, stirring to evenly coat.
Bake for 45 minutes, stirring every 15 minutes. Remove from oven and spread on wax paper or foil that has been sprayed with cooking spray. Cool completely.
In 2 separate microwave safe bowls, melt milk chocolate chips with 1 1/2 tsp shortening and white chocolate chips with 1 1/2 tsp shortening. Melt each on 50% power at 20 second intervals or using the melt function on the microwave. Stop at regular intervals to stir. Repeat process until smooth. Drizzle over the caramel corn.
Allow to dry completely then break apart. Store in airtight container at room temperature.
May use 1 Tbsp heavy cream in place of 1 1/2 tsp solid vegetable shortening, if desired