There are a million different theories about brownies and crinkle tops on the website. Here are a few reasons why you did not achieve the signature crinkle top. 1) The sugar was not dissolved enough when you whipped the eggs. Make sure to whip the eggs and sugar for at least 5 minutes until the eggs are very pale, light, and fluffy. The eggs also must be at room temperature. 2) You did not bake them fast enough. Another secret to shiny crinkle tops is to bake the brownie crinkle cookies as soon as you mix all the ingredients together. 3) It could also be due to the chocolate you used. Not all chocolate is made equally. Higher-quality chocolate will yield shinier and more beautifully crinkled tops.