Chocolate Crumble Bars

Cake Mix: Use a 15.25-ounce chocolate cake mix for the first controlled test batch and keep the brand and package size consistent while testing.
Cooling: Let the bars cool completely before slicing so the soft chocolate filling has enough time to firm up.
Chocolate Filling: Melt the filling slowly over low heat and remove it from the heat before stirring in the vanilla. Do not let the filling simmer.
Nuts: Pecans create a slightly sweeter flavor, while walnuts add more crunch and texture.
Storage: Store completely cooled bars in an airtight container at cool room temperature for up to 3 days or refrigerate for up to 5 days.
Serving: Refrigerating the completely cooled bars for about 30 minutes before slicing gives especially neat bakery-style squares. For the softest filling, let refrigerated bars come closer to room temperature before serving.

Name: Chocolate Crumble Bars
Prep time: 20 min
Cook time: 30 min
Total time: 170 min
Ingredients: 1 box chocolate cake mix; ⅓ cup vegetable oil; 1 large egg; 1 cup walnuts or pecans; 1 can sweetened condensed milk; 1 cup semi-sweet chocolate chips; 1 teaspoon vanilla extract; 1 pinch salt

The center of these bars stays gooey between two tender chocolate crumble layers. Cool the pan completely before cutting, so each rich little square holds together.

By Betty Lou Gardner2 hr 50 minUpdated 2026-08-25

These Chocolate Crumble Bars are rich, gooey, and layered with soft chocolate filling tucked between a tender chocolate crumble crust and topping! Easy to slice into little squares once cooled, they’re the kind of old-fashioned dessert bars that disappear quickly at potlucks, holidays, and family gatherings.

Betty Lou Gardner in a family archival photograph

Granny’s Kitchen Notes

From Betty Lou Gardner

I usually let these cool completely before cutting because the chocolate filling stays awfully soft while they’re still warm. Sometimes I use pecans instead of walnuts depending on what happens to be sitting in the cupboard that day.