01 -
Set your oven to 350°F (175°C). Prep a 9×13-inch pan by greasing it or lining it with parchment paper so the bars are easier to lift out.
02 -
In a big mixing bowl, toss the yellow cake mix, melted butter, and egg together. Stir until it's crumbly but mixed.
03 -
Take two-thirds of the crumbly dough and press it firmly into the baking pan, making an even layer.
04 -
Drizzle the condensed milk over the crust. Carefully spread it so it covers everything.
05 -
Scatter the chocolate chips and toffee bits across the condensed milk layer as evenly as possible.
06 -
Break the rest of the dough into small pieces and scatter them on top.
07 -
Pop it in the oven for 25–30 minutes. It should turn golden brown, with crispy edges and a soft center.
08 -
Take it out of the oven and let it cool all the way in the pan. Slice into bars and dig in!