I experimented a little with this and this is what I came up with.
I made a pumpkin custard. First I mixed canned pumpkin with cinnamon, clove, and allspice and then spread it thinly on a cookie sheet. I baked in the oven for about a half hour to roast it up a bit and get rid of some of the moisture. While that was in the oven I made a basic creme anglais with creme, egg yolks, and vanilla sugar. I added the roasted pumpkin to the creme and stirred off heat until smooth. Had to double the sugar in the custard recipe to accommodate the addition of pumpkin. The custard was superb and delicious.
I made the tart shell by grinding up gingerbread cookies, mixing with melted butter and formed into the tart shell then baked until set, about 10 minutes. I let the shell and the custard cool then I spooned the custard into the shell and topped with roasted walnuts and let it chill.
Results: excellent custard, but the tart shell is very very hard, it can only be broken through, not cut through easily at all. I'm not a baker and I have no idea how to fix that. So I have pumpkin custard, what can I do with it?