This may have already been answered by someone, but I'm needing to make a grooms cake that feeds 100 people. I only have the 11x15 Wilton performance pan and there is no way to get 100 servings from that. I will go and purchase the 12x18 Wilton pan and wonder if anyone has ever been able to get 100 servings from this pan. I found a cutting guide on pinterest and there is a guide that shows 108 servings from a 12x18 pan cutting is "wedding style". Is this possible? Any suggestions if not? They want a 2 layer sheet cake.

A two layer 12 by 18 serves 98 slices that are 1 by 2 by the height of you cake so that would be fine.  I don't know what you have in mind for the board but if you are having something custom made for it you could use the 11 by 15 two layer and then make one more layer that is 11 by 15 and cut it in half either width wise or length wise and place it along side making one bigger cake.  The 11 by 15 serves 74, and another half would be 37 so would total 111 servings. 

Thank you so much...this helps a lot. I will prepare the 12x18 2-layer cake.