Cocoa powder is essential for creating rich, chocolate-flavored biscuits. Its fine texture incorporates evenly into dry ingredients, ensuring a consistent chocolate taste throughout each batch. Natural cocoa, being acidic, provides a sharp, intense flavor and reacts with baking soda for a lighter rise and delicate crunch. For a deeper, mellower taste and darker color, Dutch-processed cocoa is ideal, though it may require baking powder. Beyond flavor, cocoa contributes to the biscuit's appealing brown hue and tender crumb structure by balancing the gluten development from flour. It is the foundation for any classic chocolate biscuit.