Line a 9x13 pan with foil and lightly coat the foil with nonstick cooking spray.

Set aside.

For the cookie layer: Whisk the melted butter and sugars in a large bowl until combined.

Add the egg, egg yolk, and vanilla and mix well.

Add the flour, salt and baking soda, folding into the dough with a rubber spatula; do not over mix.

Fold in the chocolate chips until combined.

Use lightly moistened hands to press half of the dough into a thin even layer in the prepared pan, filling in any holes with a bit of cookie dough from the bowl.

For the fudge filling: In a microwaveable bowl, combine the sweetened condensed milk, chocolate chips, and butter.

Microwave for 1 minute at 50% power.

Stir.

Microwave for another minute and stir.

If needed, repeat until the mixture is smooth and melted together.

Pour the fudge mixture over the layer of cookie dough in the pan.

Spread evenly.

Sprinkle with toffee bits.

Using the remaining cookie dough, flatten tablespoon sized amounts of cookie dough in your hands into flat disc shapes, about 1/8- to 1/4-inch thick.

Place these discs over the top of the fudge layer.

The top doesn't need to be completely covered, just make sure it is mostly covered with cookie dough.

Sprinkle evenly with toffee bits.

Bake the bars for about 35 minutes, until very lightly browned on the edges. Let cool completely on a wire rack.

Cut into squares and serve.