Prepare the pastry cream and place in the refrigerator to chill until ready to use.
Prepare a crust with either traditional pie pastry or a cookie crumb crust. If using traditional pie pastry, blind-bake until fully cooked and allow to cool completely. If using a cookie crumb crust, you can either leave it unbaked or bake the crust and allow it to cool fully.
Pour the pastry cream into your prepared crust. The pastry cream does not need to be completely cool, but do not add it when it is extremely hot.
Place a piece of plastic wrap on top of the filling and refrigerate until completely cool (at least 2 hours).