Prep time is just 15 minutes for these bar cookies because they start with purchased yellow cake mix. Add in cashews or pecans, brown sugar, toffee pieces, butter and eggs, and you've got a quick blondie-style dessert.
Preheat oven to 350 degrees F. Grease a 15x10x1-inch baking pan; set aside.
In a large bowl, combine cake mix, brown sugar, melted butter, and eggs. Beat with an electric mixer on medium speed for 1 minute or until combined, scraping bowl occasionally. Stir in the cashews.
Pat dough into prepared pan. Sprinkle with toffee pieces. Bake in the preheated oven for 15 to 20 minutes or until a toothpick inserted in center comes out clean. Cool completely in pan on a wire rack. Cut into bars. Makes 32 bars.
Place bars between sheets of waxed paper in an airtight container; cover. Store at room temperature for up to 1 week or freeze for up to 2 months.