"Cake mix bar cookies are fast and easy to put together, a nice alternative to cake. The rocky road bar comes out soft and chewy and holds together well for potlucks, school, or work lunches. Rich, creamy, and chocolaty cake mix bar cookies are an indulgent treat."
Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan.
Mix cake mix, oil, and egg together in a bowl. Spread batter into the prepared pan.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 15 minutes. Remove pan and leave oven on.
Pour frosting into a microwave-safe bowl. Cook in the microwave until warmed through, about 30 seconds. Pour frosting over the baked cake mix crust. Top with 1/2 the chocolate chips and 1/2 the almonds. Add marshmallows to cover. Top with remaining chocolate chips and almonds.
Bake in the hot oven until top is a nice golden brown, about 10 minutes. Let cool before cutting.