Sheila's Best Apple Crisp (No Oats)

"This is the apple crisp from my childhood (there is no oatmeal in the topping). If I could only pick one dessert to make the rest of my life, this would probably be it. Mom always made this in her beautiful copper au gratin pan. I bought the same pan when I got married, just so I could make this dessert. Originally from the 1966 version of the "Woman's Day Encyclopedia of Cookery", Mom adapted it slightly over the years (with a little help from Cooks Illustrated I think). Cutting the apples into "cubes" (instead of slices) helps the apples keep the apples firm throughout. I have made this with pecans or walnuts. I have also made it without nuts. I like it best with pecans, but all versions are yummy!! I love it warm or cold. You can serve it with ice cream, but I usually only do that for dinner parties...."