In a saucepan over medium heat melt the butter.
Once the butter is melted, it will begin to foam.
Continue to heat the butter until the foam subsides, and brown specks form on the bottom of the pan.
Once the brown specks form and the butter appears amber and smells nutty, immediately remove from heat. Let butter cool completely.
Preheat oven to 350 degrees. Line baking sheet with parchment paper.
In a bowl with an electric mixer, combine the cooled brown butter with the brown sugar and granulated sugar. Cream together until well blended, about 1 minutes.
Mix in the egg, egg yolk, milk and vanilla until well combined.
In separate bowl combine the flour, baking soda, and salt and then add to butter mixture.
Mix until well combined.
Using a spatula fold in chocolate chips, and toffee chips.
Scoop 2 tablespoon balls of dough onto a cookie sheet.
Bake in preheated oven for 10 minutes, or until just golden along the edges.
Be careful not to over bake.
Remove from oven, and allow to cool for 5 minutes then transfer cookies to cooling rack to cool completely.
Enjoy!