Hi! I bake cookies in a conventional oven. I am used to bake them using one baking sheet, positioning the oven rack in the middle of the oven (375 F for 11-12 min depending on the kind of cookies). Cookies turned out great! Recently I started practicing baking two sheets at once. I divided the oven into thirds, baked cookies in the first and second third (from the top), and rotated the sheets halfway through baking. However, the bottoms of the cookies were too brown and the tops were under-baked. I increased the time up to 2 min, tried to rotate them in different time, but still cookies were not perfect and I couldn’t reach the consistency. Plus, when i put 12 cookies on one pan they spread out too much. I usually use about 1.6-1.8 oz of cookie dough to get 2 inch diameter cookie. I tried to bake on 15x21 Nordic Ware Natural Big Sheets, and then 15-21 Vollrath sheet with rims. They are both light-colored, and I also always use white parchment paper. I will really appreciate if your can help me with any advises how to get great and consistent cookies baking 2 sheets at one time. And what pans would you recommend to use? Thanking in advance.