Preheat your oven to 350°F (175°C). Grease a 9 x 13-inch baking pan and set it aside.

Prepare the Dough:

In a large mixing bowl, cream together the butter and brown sugar until light and fluffy.

Add the vanilla extract and egg yolk, and mix until well combined.

Add Dry Ingredients:

In a separate bowl, whisk together the all-purpose flour and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until a soft dough forms.

Press into Pan:

Press the dough evenly into the prepared 9 x 13-inch pan, creating a smooth and even layer.

Bake:

Bake in the preheated oven for 20-25 minutes or until the edges are golden brown and a toothpick inserted into the center comes out clean.

Add Chocolate Topping:

While the bars are still warm, sprinkle the milk chocolate chips over the top.

Allow the chocolate chips to soften for a few minutes, then spread them evenly over the bars using a spatula.

Cool and Cut:

Allow the toffee bars to cool completely in the pan.

Once cooled, cut into squares or bars.

Serve:

Serve and enjoy these delicious toffee bars!

Feel free to adjust the baking time based on your oven and keep an eye on the bars as they bake to ensure they don't overcook. Enjoy your homemade toffee bars!