how to prepare 11X`15 cake pan

Hello!  Thank you for your question.

The best way to remove a cake from an 11X15 pan, or a jelly roll pan, is to first line the pan with parchment paper or foil.  You then need to grease the parchment/foil with cooking spray or butter, then pour and spread out the batter onto the pan.

Bake the cake until a toothpick inserted comes out clean and the cake starts to release from the sides.  Carefully stick a spatula underneath the cake, exposing the foil/parchment sheet.  You can then get underneath the whole cake and remove in a whole piece.  The cake can then be inverted or used however you need.