How to Make It
Heat a Dutch oven over medium-high heat. Add oil to pan; swirl to coat. Add popcorn; cover and cook 3 minutes or until kernels pop, shaking pan frequently. When popping slows down, remove pan from heat. Let stand 1 minute or until popping stops. Pour popcorn into a large bowl coated with cooking spray.
Combine sugar and next 4 ingredients (through salt) in a medium, heavy saucepan. Cook over medium-high heat until a candy thermometer registers 300°. Remove from heat; stir in vanilla. Add mini marshmallows and chocolate chips to popcorn. Immediately pour hot syrup over popcorn mixture; toss well to coat. Cool slightly (about 1 to 2 minutes). Carefully form mixture into 8 balls, being careful not to compact too tightly.