Brown the Butter: Melt the unsalted butter over medium heat, stirring until nutty brown, about 5–7 minutes. Transfer to a bowl and let cool.

Combine Sugars: Mix in granulated and dark brown sugars until fully combined and glossy. Let it reach room temperature, about 10–15 minutes.

Mix Dry Ingredients: Whisk all-purpose flour, bread flour, baking soda, baking powder, sea salt in a separate bowl for about 3–5 minutes.

Incorporate Wet Ingredients: Whisk in eggs and vanilla extract into the sugar mixture until smooth. Fold in dry ingredients, mixing just until combined.

Add Mix-Ins: Fold in chopped chocolate and toffee bits, wrap the dough in plastic, and refrigerate for at least 24-72 hours.

Preheat Oven: Allow the dough to soften at room temperature while preheating oven to 350°F (175°C) and lining baking sheets with parchment paper.

Shape and Bake: Scoop dough onto prepared sheets, spaced 2 inches apart. Bake for 12–14 minutes until edges are golden.

Shape Cookies: Use a cookie cutter to refine shape after baking, sprinkle flaky sea salt, and cool cookies on wire racks for 10 minutes.