Preheat oven to 350°F. Grease your skillet using butter or oil to keep the brownie from sticking.
In a mixing bowl, beat egg, Greek yogurt, nut milk, and vanilla extract until combined.
Beat in brown sugar and white sugar.
Fold in cocoa powder, all purpose flour, salt, and baking powder.
After the batter is thoroughly mixed, fold in chocolate chips.
Pour batter into your well greased skillet.
In a microwave safe bowl, crumble 2 sheets of honey graham crackers. Place a tablespoon of butter in the bowl and microwave for 30 seconds. Use a fork to combine crackers and butter. Sprinkle over uncooked brownie.
Bake for 18-20 minutes or until the middle is cooked.
Once the brownie is done cooking, turn off the oven and turn on the broiler. Add marshmallows on top of your cooked brownie and place on the top rack of the broiler. Broil for 2-4 minutes or until marshmallows are a golden brown. Be sure to watch closely as they can burn easily!