Make Brown Butter: In a large pan, melt butter over medium-low heat. Cook until golden brown bits begin to form at the bottom, about 5-10 minutes. Remove from heat and let cool completely. To speed up the cooling process, place in the fridge for 10 minutes.
Preheat oven: Preheat the oven to 350℉. Line a baking sheet with parchment paper or a silicone mat.
Mix Dry Ingredients: In a small bowl, whisk together flour, baking soda, and salt.
Cream Butter and Sugar: In a large bowl, cream together the cooled brown butter with the brown and white sugars.
Add Egg Yolk and Vanilla: Mix the egg yolk and vanilla until well combined.
Stir in Dry Ingredients: Gradually mix the flour mixture into the wet ingredients until fully incorporated. Stir in ½ cup of toffee bits. The dough will be crumbly.
Press Dough into Pan: Place the dough in the middle of the baking sheet and press it into an even layer, covering the entire pan. Place a sheet of parchment on top and use a rolling pin to ensure the dough is evenly spread out.
Bake:Bake for 11-13 minutes or until golden brown.
Add Chocolate: Remove from the oven and sprinkle the chocolate chips over the top. Return to the oven for 1-2 minutes or until the chocolate has softened. Remove from the oven and use a offset spatula to spread the melted chocolate into a thin even layer over the cookies. Sprinkle the remaining 1/2 cup of toffee bits over the top.
Cool and Break: Let the cookies cool in the fridge until the chocolate is set, about 30-45 minutes. Once fully set, break the cookie bark into pieces.