225g (1 Cup) Cold Butter: Unlike many recipes, we use cold, cubed butter here. This prevents the cookies from spreading too quickly in the oven.150g (3/4 Cup) Brown Sugar: This provides moisture and the typical caramel note.100g (1/2 Cup) White Sugar: Responsible for the slightly crispy edges.2 Large Eggs: Directly from the fridge to keep the dough temperature low.400g (approx. 3 1/4 Cups) All-Purpose Flour: The base for the structure.2 tsp Cornstarch: The absolute secret to the "crumble" texture. It makes the dough more tender and prevents excessive gluten formation.1 tsp Baking Soda & 1/2 tsp Baking Powder: For the perfect lift.1 tsp Sea Salt: To balance the sweetness of the chocolate.300g (2 Cups) High-Quality Chocolate Chips (Dark or Milk): Large chunks ensure the best "chocolate pools."