A question about a recipe: CHOCOLATE CARAMELIZED ORANGE TART

I have a question about step 2 on the recipe "CHOCOLATE CARAMELIZED ORANGE TART" from Ginger's Kitchen. It says:

"MAKE CRUST: Place cookies in a food processor and pulse until it becomes like a coarse meal. Spray a regular pie pan with cooking spray and then press the cookie mixture into the pan - on the base and up the sides." --what is the butter used for, is it melted and added to the crumb crust? Thanks for your help!!!