Rocky Road Blondies with Brown Sugar Crackle

Most of the time I like my sweets not actually that sweet, but once in a while I crave something chewy, gooey and unabashedly American-type sweet. These bars answer that call with a toothsome blondie topped with a good helping of marshmallows, chocolate and nuts. The added bonus is a baked meringue-like brown sugar topping that cracks when you cut (or bite!) into it. That technique and the inspiration for these blondies are from an old recipe called Double Chocolate Mud Bars found in the early 90s cookbook Great American Home Baking. This has much of the same execution with thicker base to add more chew and let’s be honest, more sweetness in each bite. The one thing to note is there is not the usual toothpick trick to test for doneness, as the marshmallow and chocolate are too gooey. As long as the top is nice and golden, you should be fine. And honestly, if the blondies are a little underdone, it just adds to the chew factor and makes them yummier.

Makes 9 to 12 bars


  • 8 tablespoons (113 grams) unsalted butter
  • 1 ½ cups (324 grams) brown sugar, divided
  • ½ cup (100 grams) granulated sugar
  • 1 large egg (50 grams)
  • ½ teaspoon vanilla extract
  • 1 ½ cups (195 grams) all-purpose flour
  • ½ teaspoon baking powder
  • ½ teaspoon salt
  • ¾ cup (128 grams) semisweet chocolate chips
  • ½ cup (39 grams) chopped walnuts
  • 1 cup (50 grams) mini marshmallows
  • 2 large egg whites (60 grams)


Make the Bars:

  1. Preheat the oven to 350ºF. Grease an 8-inch square pan, line with parchment allowing a 2-inch overhang on the sides and spray again. Set aside.
  1. Melt the butter in a microwave safe bowl or in a small saucepan over medium heat.
  1. Add the melted butter, ½ cup of the brown sugar and all of the granulated sugar to a medium sized mixing bowl and combine with a spoon or hand mixer.
  1. Add the egg and vanilla extract, mixing until combined.
  1. In a separate small bowl, combine the flour, baking powder and salt and then add to the butter mixture. Stir until just combined, being careful not to overmix.
  1. Press the mixture evenly into the bottom of the prepared pan. Sprinkle with the chocolate chips, walnut and then marshmallows.
  1. In a small clean bowl, whip the egg whites to firm peaks, sprinkle with the remaining cup of brown sugar, whisking to combine. Pour the mixture as evenly as possible over the toppings. Bake for 35 minutes or until the top is golden brown and very puffy.
  1. Remove and allow to cool entirely before removing from the pan. Use the parchment to help guide the bars out, cut with a serrated knife and serve. Leftover bars can be stored at room temperature in an airtight container for up to 3 days.


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AnnMarie Mattila
AnnMarie Mattilahttps://pastryathome.com
AnnMarie Mattila is a writer for Pastry Arts Magazine, as well as a freelance baker and pastry chef in New York. She has a master’s degree in Food Studies from New York University and is also a graduate of the Institute of Culinary Education.

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