In my third year of trying, I finally managed to procure a green pumpkin to make green pumpkin pie with.
For those who need background: in The Long Winter, the Ingalls family is surprised by an early freeze, and most of their garden is ruined before much was harvested. But they save what they can--the potatoes are fine, some of the tomatoes are ripe, and Ma makes pickles out of the green ones. And there's a bushel of beans. (They think they have enough food to last through the winter, but they DON'T, and when you reread this you know, and it is all scary foreshadowing.)
A few of the pumpkins are ripe, but most are green. Ma's wheels must be turning, because as soon as Pa leaves to go hunting...
After he had gone, Ma said "Girls, I've thought of a surprise for Pa."
..."What?" they all asked her.
"Hurry and get the work done," Ma said. "And then, Laura, you go to the corn patch and bring me a green pumpkin. [wonder if Ma realizes that growing squash and corn together is an "Indian idea"?] I'm going to make a pie!"
"A pie! But how..." Mary said, and Laura said "A GREEN pumpkin pie? I never heard of such a thing, Ma."'
"Neither did I," said Ma. "But we wouldn't do much if we didn't do things that nobody ever heard of before."'
Laura and Carrie did the dishes properly but in a hurry. Then Laura ran through the cool, misty rain to the corn-patch and lugged back the biggest green pumpkin.
(I used only two pounds of this ten-pound pumpkin.)
"Now what do I do?" [Laura asked].
"You may cut the pumpkin in slices and peel them while I make the piecrust," said Ma. "Then we'll see what we'll see."
(I cut them a bit smaller than that in the end.)
Ma put the crust in the pie pan and covered the bottom with brown sugar and spices. Then she filled the crust with the thin slices of the green pumpkin. She poured half a cup of vinegar over them, put a small piece of butter on top, and laid the top crust over all.
"There," she said, when she had finished crimping the edges.
"I didn't know you could," Carrie breathed, wide-eyed, looking at the pie.
"Well, I don't know yet," Ma said...
(On the advice of the cookbook, since I didn't have any homemade vinegar around, I used hard cider instead--she says this is more similar to what Ma would have had. And I used a third cup, to allow for modern measurements. I couldn't taste any alcohol in the finished pie, and I have an extremely sensitive-to-alcohol palate.)
The pie was baking beautifully. When Ma... opened the oven, the rich smell of baking pie came out. [This was truly an amazing smell; I wish I could have taken a picture of it for all of you. It was richer and somehow more complex than that of either apple or pumpkin pie.] ...Ma turned the pie so that it would brown evenly.
"It's doing nicely," Ma said.
"Oh, won't Pa be surprised!" Carrie cried.
Just before dinner, Ma took the pie from the oven. It was a beautiful pie.
[They hoped to have it for dinner, but Pa doesn't come home, so it has to wait for supper. What a disappointment that must have been. (Mary probably thought it built character.)]
Laura set down the pie.
For an instant Pa did not see it. Then he said "Pie!"
His surprise was even greater than they had expected. Grace and Carrie and even Laura laughed out loud.
"Caroline, however did you manage to make a pie? What kind of pie is it?"
"Taste it and see!" said Ma. She cut a piece and put it on his plate.
Pa cut off the point with his fork and put it in his mouth. "Apple pie! Where in the world did you get apples?"
Carrie could keep still no longer. "It's pumpkin! Ma made it of green pumpkin!"
Pa took another small bite and tasted it carefully. "I'd never have guessed it," he said. "Ma always could beat the nation cooking."...
They ate slowly, taking small bites of that sweet spiciness to make it last as long as it could.
That was such a happy supper that Laura wanted it never to end.
The pie was tasty. I wouldn't say that it was as good as apple pie, but of course apples have never been scarce for me; and also, I was using an ordinary Halloween pumpkin, which I got for free from the patch because it would have been too scarred to sell. If I had used a pie pumpkin, I'm guessing it would have been more flavorful. The pumpkin pieces were a little bland and watery--they reminded me of the chayote squash I often had in soups in Guatemala. I was pretty skeptical about the cup of brown sugar the cookbook directed me to put in the bottom of the crust. It filled up about half the pan, and I sort of doubt that Ma would have been able to put that much sugar in. The flavor was good, but I think it would have been fine with less sugar. And as you can see, it was QUITE liquidy after being cut. I think that was probably from the pumpkin, and a tablespoon or two of flour might have improved that. I bet the extra liquid would be good on vanilla ice cream, though I think if you ate a scoop along with your pie, the ice cream would overwhelm its delicate flavors.
I discovered that the pie was even better the next day, so the Ingallses were probably better off having to wait to eat it at supper, anyway.