Step 1

Preheat the oven to 350 degrees Fahrenheit (175°C). Grease a 9x13-inch baking pan and line with parchment paper (leave some hanging over the side for easy removal).

Step 2

In a large bowl, stir the cake mix, softened butter, and egg yolk until crumbly. Press the mixture evenly into the prepared pan to form the crust.

Step 3

In a separate bowl, beat the sweetened condensed milk, whole egg, and vanilla extract until smooth. Stir in the chopped pecans and toffee bits until evenly distributed, then pour over the crust and spread flat with a spatula.

Step 4

Bake for 25-30 minutes or until the edges are golden brown and the center is set.

Step 5

Let the bars cool completely in the pan and then chill for 1-2 hours in the fridge. Use the excess parchment to lift them onto a cutting board. Slice, serve, and enjoy!