Brown the Butter by melting 1 cup of unsalted butter in a sauté pan over medium heat for 5-7 minutes until golden brown.

Mix Sugars by stirring in 3/4 cup granulated sugar and 1 cup dark brown sugar until combined.

Combine Dry Ingredients by whisking together 2 cups all-purpose flour, 1 cup bread flour, 1 teaspoon baking soda, 1 teaspoon baking powder, and 1/2 teaspoon fine sea salt in a bowl.

Combine Wet Ingredients by adding 2 large eggs, 1 extra egg yolk, and 2 teaspoons vanilla extract to the cooled butter and sugar mixture.

Incorporate Dry Mixture by gently folding the dry ingredients into the wet mixture, followed by folding in 8 ounces of chopped chocolate and 1 cup of toffee bits.

Chill Dough by wrapping it tightly in plastic and refrigerating for at least 24 hours.

Preheat Oven to 350°F (175°C) and prepare baking sheets with parchment paper.

Shape & Bake Cookies by scooping out 3-tablespoon sized balls of dough and baking for 12-14 minutes.

Finish & Cool by sprinkling cookies with flaky sea salt and letting them cool on racks.