Press the crumb mixture firmly into the bottom of a 9x9 inch baking pan that has been lightly greased and lined with parchment paper. (For a thinner version with less frosting at the centre you can use a 9x13 inch pan and get 50% more squares too. See NOTE for adjustments below.)
Since these are very rich cookie squares, You can use the same amount of filling in a 9x13 inch pan if you like. This will make the squares about 1/3 thinner, plus you will get about 1 1/2 times more servings.
Simply increase the bottom and top layers by 1 1/2 times the recipe and leave the filing as it is.
If you are freezing these cookie squares, I would suggest freezing them without the whipped cream topping and then adding the topping when thawed and ready to serve.
Although it is not my preference, many non-dairy whipped toppings will freeze pretty well if used as the top layer.
The nutritional information provided is automatically calculated by third party software and is meant as a guideline only. Exact accuracy is not guaranteed. For recipes where all ingredients may not be used entirely, such as those with coatings on meats, or with sauces or dressings for example, calorie & nutritional values per serving will likely be somewhat lower than indicated.