I will also use this for gluten-free guests at our Bed and Breakfast and farm-to-table dinners. I had a bigger egg surplus than rhubarb, so when I ran out I made an Almond Joy version with coconut, sliced almonds and a chocolate crust, a Snickerdoodle version with cinnamon and nutmeg, and a Banana Custard version. All of them puffed slightly in the pans before settling when cool, so it is best not to fill them too close to the top.
RHUBARB CUSTARD PIE
1 c. rhubarb, sliced and spread in the bottom of a 9 or 10-inch pie pan (I had a nine inch and needed to make two overflow ramekins. )
Mix all together:
4 chicken eggs or 2 goose eggs
2 c. milk (I used almond milk for the Almond Joy pie and it came out great.)
1/2 to 3/4 c. sugar, depending on your love for tart rhubarb
1/2 c. gluten-free baking mix or almond flour (don't use one that's predominantly chick pea flour - it'll be a bit bitter)
6 tbsp melted butter or coconut oil (you could probably cut this down to 4 tbsp with very little loss)
2 tsp vanilla
1/2 c rolled oats
Preheat oven to 350 degrees. Put pie plate with rhubarb on a baking sheet - the batter is very liquid and will likely be difficult to move without spilling. Bake for about 45 to 50 minutes. Top will start to brown but don't let the bottom get dark. Custard should be set up but not entirely firm. It will firm up in the fridge. Cool for about 1/2 hour on a rack in the kitchen before chilling in the fridge (unless you want to serve it with ice cream in which case serve within a half hour of removing from the oven). This isn't a super rich pie and would go nicely with some whipped cream, as well.
For the Almond Joy Pie: Skip the rhubarb and sprinkle dark chocolate chips in a sparse layer on the bottom of the pan. To the liquid, add 1 cup of shredded unsweetened coconut, 1 tsp of almond extract and trade sliced almonds for the oats.
For the Snickerdoodle Pie: Skip rhubarb and add 1 tbsp of cinnamon and 1/4 tsp nutmeg. Sprinkle with cinnamon and sugar mix when done.
For the Banana Custard Pie: Skip rhubarb and slice enough bananas to cover the bottom of a pie pan. Proceed as above.
Something I did not make for the bake sale, but most certainly will make for a farm-to-table dinner this year is a Cardamom Carrot Custard Pie. I will substitute 1 cup shredded carrots for the rhubarb and 1/2 cup sliced almonds for the oats, then add a tsp of cardamom, 1/2 tsp of sweet curry, 1/2 tsp of mace and 1/2 tsp of cinnamon. I will grate some fresh nutmeg on top. I may also put coconut flakes on top once the pie is almost finished and let them get a bit toasted.