Importing the class

Link to importing-the-class

It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import at the very top of the file.

import mods.createtweaker.CrushingRecipe;

Extending AbstractCrushingRecipe

Link to extending-abstractcrushingrecipe

CrushingRecipe extends AbstractCrushingRecipe. That means all methods available in AbstractCrushingRecipe are also available in CrushingRecipe