Roll out dough on a lightly floured surface. Work into rectangle approx. the size of the pan. Trim edges for a tidy rectangle. Gently lift and place into pan. PRess to fit all the way, right to the pan edges. Prick all over with a fork. Chill the dough for 20 minutes. Blind-bake for 15 minutes, or until it's no longer shiny, and just beginning to turn golden brown.
Once the base is blind-baked, remove it from the oven. Pour in all the apple filling and top with the streusel. Return it to the oven and bake for another 35 to 40 minutes, until the streusel is golden brown and the filling bubbles.
Allow to cool completely, then slice in squares and serve as is or with a dollop of whipped cream. If you like a delicious hot mess, don’t wait until it’s cool, just dig in right away. Store the cooled cake airtight at room temperature for 2 to 3 days or refrigerated for up to 5 days.