Spread popcorn on large rimmed baking sheet.

In a medium saucepan, combine butter, sugar, and corn syrup.

Bring to a boil, stirring constantly, and boil moderately for 4 1/2 minutes without stirring.

Remove from heat and stir in cocoa powder and baking powder.

Pour over popcorn and stir to coat.

Bake popcorn at 300 degrees for 15 minutes.

Remove from oven, stir, and bake 5 minutes more.

Cool 5-10 minutes, then add marshmallows, chocolate chips, graham cracker pieces, and graham cracker crumbs.

Store in an airtight container at room temperature.