In a large mixing bowl, using an electric hand mixer, blend the butter until smooth, then add the egg and fully incorporate. Slowly add the dry cookie mix and blend until a dough forms. Gather the dough into flat disc and wrap in plastic. Chill 20 minutes or until firm.
Remove dough from refrigerator and preheat oven to 350 degrees. Line a baking sheet with parchment paper, set aside. Unwrap dough from plastic and form into tablespoon sized round balls. Place cookie dough on parchment paper, at least one inch apart and gently press down on the top. Bake 13-15 minutes, until the edges begin to turn golden. Remove from oven, cool 5 minutes on the baking pan, then move to a wire rack to cool completely.
In a sauce pan over medium heat, melt together the butter, brown sugar, heavy cream and salt. Whisk until sugar is completely dissolved and the mixture begins to bubble. Turn the heat down to medium - low and simmer the caramel sauce 5 minutes, stirring frequently. Remove from heat and place sauce pan in the freezer to cool and thicken the caramel sauce, about 5 minutes.
Working with 6-7 cookies at a time, break the cookies up into small chunks and place into a blender. Pulse cookies until they become the texture of sand. Repeat with the rest of the sugar cookies. Put all of the cookie crumbs in a large bowl and set aside.
Pour 10 cups of popcorn into a large bowl. Pour the caramel sauce onto the popcorn and toss with a rubber spatula until the popcorn is evenly coated in the caramel. Reserve one cup of cookie crumbs, then sprinkle the rest of the cookie crumbs onto the popcorn and toss again until the crumbs evenly coat the caramel corn.
Spread popcorn in one layer onto 2 sheet pans lined with parchment paper. Bake at 350 degrees for about 10-12 minutes. Remove cookie corn from oven, sprinkle remaining cookie crumbs on top and toss gently. Allow to cool completely, then break up the large pieces with your hands and enjoy!