In medium saucepan, combine brown sugar, butter and corn syrup. Cook over high heat 5 minutes; remove from heat and stir in baking soda.
In large bowl, combine popcorn and marshmallows. Pour sugar mixture over popcorn to coat.
Gently stir in graham cookies and chocolate chips. Spread mixture evenly into greased 15-by-10-inch pan. Let cool completely. Break into pieces.
All materials courtesy of Family Features. For more creative, DIY popcorn recipe ideas, visit www.popcorn.org