This part is important. You want to use a sheet pan with at least a 1-inch lip on the outer rim. Otherwise, the liquid egg mixture will probably spill. I recommend using a sturdier baking sheet for this recipe, I used the paderno professional baking sheet and I can definitely notice a big difference in how strong it is compared to the cheap dollar store versions I've had in the past. Plus the edge is enough to properly hold the egg mixture in place.