You can certainly use mini marshmallows instead of the large size, just use about two cups. Also, feel free to use chocolate chips in place of the chopped Hershey’s Bar (probably about a cup or so).
- 3/4 cup butter (, softened)
- 1 cup brown sugar
- 1 cup old fashioned oats
- 3/4 cup flour
- 3/4 cup graham cracker crumbs
- 1 teaspoon baking powder
- 1 teaspoon kosher salt
- 1 teaspoon cinnamon
- 2 cups marshmallows (, halved crosswise (or 2 cups mini marshmallows))
- 12–14 Hershey’s snack size chocolate bars (, chopped coarsely)
- Preheat oven to 350 degrees. Spray a 10-inch cast-iron skilled with cooking spray.
- In a large mixing bowl, beat butter and brown sugar on medium speed until fluffy, about 3-4 minutes (scrape sides as needed). Add oats, flour, graham cracker crumbs, baking powder, salt and cinnamon. Mix until well combined.
- Press two-thirds of the crumble mixture into the prepared skillet. Top with marshmallows and chopped chocolate. Sprinkle with remaining crumble mixture.
- Bake until golden brown, 20-25 minutes. Let cool for 10 minutes before servings. Drizzle with melted chocolate, if desired.