1. a can of Libby's pumpkin pie mix, or canned pumpkin. Prepare as for an ordinary pumpkin pie. If you grow your own pie pumpkins, I'm sure that would work too.
2. a box of brownie mix. If it offers options, you want to make it the "fudge brownie" way, not the "cake brownie" way.
3. Pastry sufficient to line a baking dish (or, in my case, two baking dishes) large enough to handle all the pumpkin and brownie fillings. Pie pans aren't ideal, unless you have deep-dish type. It will swell up during backing, so you need clearance at the top--you can't fill all the way to the rim. Leave about 1/2 inch. I used store-bought refrigerated pastry (Pillsbury) in square ceramic baking dishes.
4. Brownie batter is a lot denser than the pumpkin filling batter. This allows a variety of possibilities for an interesting interior. If you put the pumpkin in first, the brownie batter will sink through it, and as it bakes, the displaced pumpkin will cover, or almost cover, the brownie batter...so the cut pie will have interesting "sandwiching" of the brownie by the pumpkin. If you put the brownie batter in first, you get layers. You can dribble a little of the brownie batter on top without it sinking, for a decoration. This was my first time to try it, so I didn't make full use of the decorative possibilities. Next time, I'll try dropping spoonfuls of brownie batter at intervals on the pumpkin, to make smaller, less regular "blobs" of brownie in the pumpkin.
5. Baking time is LONG. I used the pumpkin pie directions (15 minutes at 400 degrees F, but because I was interrupted by a guest, it was more like 20, and then turn it down to 350 for the rest of the time. ) It definitely took longer than the pumpkin pie directions and I may have overbaked a little (not sure of the time--guests were arriving, and we were running back and forth between houses and kitchens so I lost track) but the total time is definitely more than an hour.
6. We hauled the pies to the house where the dinner actually was right before we sat down to eat, and they were cool enough to eat when we'd finished with the turkey. The pies smelled wonderful and looked enticing. In the one where I'd put the pumpkin in first, a bit of the sunken brownie had come through the top, which really looked great. The brownie part was still faintly warm and soft (but not really gooey), perfect inside the pumpkin. Whipped cream (the real thing, not whipped topping) was the perfect accompaniment. I ate way too much of it (which is how I know it's richer than you think when you first taste it.)
Compared to pumpkin-chocolate recipes that require you to melt chocolate and so on, this seemed very easy to me. The guests who tried it like it a lot. It does make a LOT of pie. We ate only one yesterday (we had other pies people had brought, too, so we had more pie than the assembled group could possibly eat in one meal. I think next time I'll use one big baking dish, and plan to chill completely and cut into smaller squares. And I won't make regular pumpkin and brownie-fudge pies at the same time!