Rhubarb and Berry Swamp Pie

In working through The Book on Pie by Erin Jeanne McDowell with the Rainy Day Bites Cookbook Challenge, I encountered a pie that I had never heard of - the swamp pie. McDowell learned of the swamp pie from a colleague at Food52 when she made a Raspberry Swamp Pie with two crusts, which was topped with custard mid-bake, and baked until set. McDowell took that idea, changed the berry, and tweaked it to have a streusel top instead. Her adaptation is the recipe in her cookbook and on Food52 (along with a very useful instructional video on this pie but also custard pies in general.) I have had rhubarb in the freezer begging to be used during the spring, so I decided to make a rhubarb adaptation. I decided 1.5 pounds of blueberries would be roughly 4 1/4-4 1/2 cups fruit, so I went with 3ish cups of rhubarb, 1ish cup of blueberries from last summer's garden, and the leftover raspberries from our Saturday breakfast (pancakes, always.)

 

Blueberry (& Rhubarb!) Swamp Pie

Ingredients  

        Streusel Topping

• ¹/₂ cup (40 grams) old-fashioned oats
  
• ¹/₂ cup (60 grams) all-purpose flour
  
• 2 tablespoons whole-wheat flour*
  
• ¹/₂ cup (53 grams) light brown sugar
  
• ¹/₄ teaspoon baking powder
  
• ¹/₄ teaspoon fine sea salt
  
• ¹/₄ teaspoon ground cinnamon
  
• 4 tablespoons (57 grams) cold unsalted butter, cut into 1/2-inch cubes
  

        Blueberry Filling

• 1 ¹/₂ pounds (680 grams) fresh blueberries*
  
• Zest and juice of 1 lemon
  
• ¹/₂ cup (99 grams) granulated sugar
  
• 1 vanilla bean, halved and scraped (or 2 teaspoons vanilla extract)
  
• 3 tablespoons all-purpose flour
  
• ¹/₂ teaspoon fine sea salt
  
• 1 par-baked pie crust
  
  Custard Filling
  
  
• ³/₄ cup (171 grams) heavy cream
  
• 2 tablespoons light brown sugar
  
• 1 large egg (57 grams)
  
• 1 teaspoon vanilla extract

 Directions

1. Heat the oven to 375°F with a rack in the lower third of the oven (preferably with a baking steel or stone on it). Stir all the ingredients for the streusel together to combine, then add the butter and cut it into the mixture until it forms large clumps.
2. In a medium bowl, toss the blueberries with the lemon zest and juice. (If using vanilla extract instead of vanilla bean, add here, too.)
3. In a small bowl, mix the sugar and vanilla bean scrapings with your hands, rubbing the two together to disperse the seeds. Stir in the flour and salt, then sprinkle this mixture over the blueberries, stirring until well combined.
4. Pour this mixture into the cooled par-baked pie crust and arrange in an even layer. Sprinkle the streusel evenly over the top of the pie.
5. Transfer the pie to the oven (on top of the steel/stone, if using). Bake until the crust is deeply golden and the berries are juicy and bubbly, 35 to 40 minutes.
6. Just before the pie reaches the 35 minute mark, make the custard filling. In a medium bowl, whisk the cream, brown sugar, egg, and vanilla to combine. When the pie reaches the doneness listed in step 4, pull out the oven rack and gently pour the cream mixture all over the surface of the bubbling pie. If the cream looks like it’s going to overflow over the edge of the crust, make a small hole with a paring knife to give you a spot to pour the custard, then slowly pour the custard into the well. Don’t go too fast, or it will overflow instead of sinking into the pie.
7. Return the rack to the proper place and continue to bake until the custard is set around the edges but slightly jiggly in the center, 10 to 15 minutes more. Let cool completely before slicing and serving.

 

Notes from JennyBakes:

- I used a pate brisee crust in hopes it would par bake without shrinking (and I used dried beans as pie weights) - this worked! She recommends an all-butter crust but I was not feeling that confident.

- I don't really keep whole-wheat flour on hand, so I just used 2 more tbsp all-purpose flour. I could have used a nut flour instead and that would have added a bit more texture. No big deal.

- As described in my intro, I think you can use a scant 4.5 cups of almost any fruit you'd usually bake in a pie instead of the blueberries.

- Because I used frozen fruit, I had to bake this pie so much longer than the directions called for. Like 30 minutes longer. But it didn't burn, although I probably could have waited longer to add the custard. My fruit in the middle was not yet bubbling when I added it.

- If I made this combo again, and I would, because it was tasty, I might add a bit more sugar since rhubarb alone is not very sweet.