Why It Works
- A mix of wild and cultivated blueberries gives the filling incredible depth of flavor.
- Tapioca starch forms a light, clear gel that's never cloudy, slimy, or gloppy.
- A 4:1 ratio of fruit to sugar raises tapioca's gelatinization point so the filling and crust will cook at the same rate, meaning you never have to trade a thick filling for a soggy crust!
- Tempered-glass pie plates conduct heat quickly and evenly to the dough, producing a far crispier crust than heavy ceramic or stoneware.
Despite what a certain reputable but totally unnamed source would have you believe, picture-perfect blueberry pie is ridiculously easy to make. That's because blueberries aren't some mystery of the universe, filled with variables no man can account for; they're filled with water. Tasty water, to be sure, but water that can be accurately gauged thanks to something known as a scale.
Whether it's fresh or frozen (more on that here), a fruit's weight gives us a reliable indication of its water content, so we can easily predict how much starch is needed to form a gel and how much sugar is needed to protect that starch from thermal hydrolysis, a.k.a. overcooking. You can read up on the science behind my formula here, but in practice all you have to know is this: Whatever your fruit, you'll need 5.5% of its weight in tapioca starch and 25% of its weight in sugar, tossed in a crust, baked until bubbling-hot, and cooled to 85°F (29°C). With those rules, you can always count on a pie that's juicy yet beautifully thick, never runny or gloppy.
Truth be told, it doesn't matter whether you've got blueberries, cherries, or plums, because water is the only factor we need to account for when it comes to thickening a pie. But wait, you cry. What about pectin? Doesn't that, like, have something to do with pie?
Ehhh, not really. For the uninitiated, pectin is a soluble fiber found in many fruits, and when cooked it can help liquids to gel. It's only natural to imagine this natural thickener must play an important role in fruit pies, but pectin is a little fussy, willing to perform only under specific conditions. Aside from concentration, which varies from fruit to fruit, pectin requires just the right amount of sugar, acidity, and heat before it can really kick into gear.
According to my pal Cathy Barrow, author of Mrs. Wheelbarrow's Practical Pantry, pectin doesn't really do its thing until about 220°F (104°C). That's well above the internal temperature of any pie, significantly hampering pectin's power to gel. What's more, compared with jams and jellies, pie filling contains way less sugar and acid—two more factors that minimize pectin's role as a thickener.
So while it's true that blueberries contain a decent amount of pectin, it's of little use within the context of a low-sugar, low-acid, low-heat pie. Put simply, when it comes to blueberry pie, pectin is completely irrelevant. That means blueberry pie is dead easy to thicken, because there aren't any wild cards to consider.
Some bakers thicken their pies by cooking down the berries' juice to concentrate the flavor, but to me that makes for a jammy pie that's thick but also a little dry. Others prefer a pie so juicy it needs to be served with a spoon. My recipe offers the best of both worlds: a blueberry pie that's lusciously thick and easy to slice, but with all its natural juices intact. It also needs a crispy, flaky, golden crust on the top and bottom, without requiring any par-baking. Of course, that's not a feat any old recipe can achieve, but with my old-fashioned flaky pie dough, you'll never have to worry about a soggy bottom crust again.
How to Make the Best Blueberry Pie
20 ounces fresh blueberries (3 1/4 cups; 565g)
8 ounces wild blueberries (2 cups; 225g), fresh or frozen (see note)
1 ounce fresh juice from 1 lemon (2 tablespoons; 30g)
7 ounces sugar (1 cup; 195g)
1/2 teaspoon (2g) Diamond Crystal kosher salt; for table salt, use half as much by volume or use the same weight
1/4 teaspoon ground coriander (optional)
1 1/2 ounces tapioca starch (1/3 cup plus 1 teaspoon; 40g), such as Bob's Red Mill (see note)
Old-Fashioned Flaky Pie Dough, rolled and chilled as per the directions for a double crust
For the Egg Wash (optional):
1 large egg
1 large egg yolk
1/2 ounce heavy cream (1 tablespoon; 15g)
1/8 teaspoon (0.5g) Diamond Crystal kosher salt; for table salt, use half as much by volume or use the same weight
To Serve (optional):
For the Filling: Toss regular and wild blueberries, lemon juice, sugar, salt, coriander (if using), and tapioca starch in a large bowl, folding with a flexible spatula until well combined. Scrape into prepared pie shell and top with remaining dough, using a solid sheet, cutouts, or a lattice-top design. (Check out my tutorial here.) Trim away excess dough and refrigerate to ensure top crust is completely chilled, about 30 minutes. Meanwhile, adjust oven rack to lower-middle position and preheat to 400°F (200°C).
For the Egg Wash (if using): Whisk egg, egg yolk, cream, and salt in a small bowl. Brush over chilled top crust in a thin, even layer. This will give the crust a glossy, golden sheen, but it is not necessary in any way.
Place chilled pie on a parchment-lined half-sheet pan. Bake until crust is golden, about 1 hour, then loosely cover with tented foil. (Alternatively, an empty baking sheet can be placed on the topmost rack of the oven to serve as a shield.) Continue baking until filling is bubbling even in the very center of the pie, about 15 minutes longer. If crust completely covers filling, bake until pie reaches an internal temperature of 213°F (101°C) on a digital thermometer. The time can vary considerably depending on the thickness and type of pie plate, the amount of top crust, how long the pie was refrigerated, et cetera.
To Serve: Cool pie until no warmer than 85°F (29°C) on a digital thermometer, about 3 hours depending on the type of pie plate (at higher temperatures, filling will be runny and thin). Slice into wedges with a sharp knife, pressing firmly against bottom and sides of pie plate to ensure the bottom crust is completely cut. If you like, serve with Lemon Chantilly. Wrapped in foil, leftovers will keep up to 3 days at room temperature; warm 10 minutes in a 350°F (180°C) oven to revive crust before serving.
9-inch pie plate (preferably tempered-glass), pastry brush, rimmed half-sheet pan, digital thermometer
Due to disparate sourcing practices, tapioca starch manufactured in Asia may be derived from plants other than cassava, which may have different gelling properties. Look for products that mention cassava by name on the packaging, such as Bob's Red Mill.
Whether you've got top-notch local berries or run-of-the-mill supermarket fruit, smuggling a portion of wild blueberries into the mix makes for a pie that's remarkably complex. If they're not growing in your own backyard, look for wild blueberries in the freezer aisle of well-stocked groceries like Kroger or markets such as Whole Foods and Trader Joe's. There's no need to defrost them before using. Of course, that's not to say you can't make a perfectly excellent pie using cultivated blueberries alone; only that you should probably make two pies to taste the difference side by side. You know, for science. If you'd prefer to skip the wild blueberries, simply increase the "normal" blueberries to 28 ounces (5 2/3 cups; 795g), fresh or frozen.
Prep time will fluctuate depending on the complexity of crust design.
|Nutrition Facts (per serving)|
|Servings: 8 to 10|
|Amount per serving|
|% Daily Value*|
|Total Fat 17g||22%|
|Saturated Fat 6g||29%|
|Total Carbohydrate 64g||23%|
|Dietary Fiber 4g||14%|
|Total Sugars 27g|
|Vitamin C 7mg||35%|
|*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.|