Step 1: Break the cookies into smaller pieces, and add them to a large, heavy-duty Zip-Lock baggie. (Two bags might be necessary, depending on the size of the bags.)
Step 2: Press down very gently on the bag to push the air out, and seal the bag.
Step 3: Use a rolling pin to crush the cookies further by gently rolling over the bag.
Step 4: When the cookies are in mostly the size of small crumbs, pour them into a medium-sized mixing bowl.
Step 5: Add the melted butter and mix to blend.
Step 6: Pour the cookie mixture into a pie plate and, using your hands, press it to evenly coat the bottom and sides. Put the plate in the freezer until firm, at least 15 minutes.
Step 7: Soften the first 1½ cups of ice cream for the bottom layer of the pie. You can do this by either leaving it out at room temperature, or by microwaving it for about 15 seconds. Spread the ice cream directly on top of the crust.
Step 8: Place the pie plate back in the freezer until it has completely frozen, about 40 minutes.
Step 9: Repeat this twice more with the remaining two flavors of ice cream. (You can layer the ice creams in any order you'd like.)
Step 10: Serve! (You can make this up to 4 days ahead of time, keeping it frozen and wrapped tightly.)
Note: If Dad only has one or two favorite ice cream flavors, that's great, too. You can use any number you'd like, as long as it totals about 4½ cups.
More Father's Day Ideas: