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A sheet pan filled with a flag pie made with strawberries, blueberries, and pie crust.
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5 from 5 votes

Flag Pie (Blueberry-Strawberry)

Flag Pie (aka sheet pan or slab pie) is a patriotic dessert that serves 20 people as a July 4th dessert or for summer cookouts and picnics.
Prep Time30 mins
Cook Time45 mins
Total Time1 hr 15 mins
Course: Desserts & Sweets
Cuisine: American
Keyword: flag pie, sheet pan pie, slab pie
Servings: 20
Calories: 256kcal

Ingredients

  • 5 pie crusts 4 pie crusts - for the bottom crust and 1 pie crust for stars and stripes
  • ¼ cup fine sugar
  • 2 13 x 18 large sheet pans
  • 1 ruler
  • parchment paper

strawberry pie filling

  • 2 quarts (8 cups; 4 - 16 oz boxes) fresh strawberries, hulled and quartered
  • ½ cup sugar
  • 4 teaspoons tapioca flour
  • teaspoon salt
  • 1 tablespoon lemon juice
  • 1 teaspoon lemon zest

blueberry pie filling

  • 2 cups (1 pint) fresh blueberries (or frozen blueberries)
  • 2 tablespoons sugar
  • 1 teaspoon tapioca flour
  • 1 ½ teaspoons lemon juice
  • 1 teaspoon lemon zest

Instructions

  • Prepare sheet pans, lightly spray one sheet pan coconut nonstick spray, line the other with parchment paper.
  • Preheat the oven to 425 degrees.

blueberry pie filling

  • Rinse the blueberries, and mix all the blueberries, sugar, tapioca flour, lemon juice, and lemon zest ingredients in a bowl, set aside.
  • Keep the blueberry pie filling separate from the strawberry filling.

strawberry pie filling

  • Rinse the strawberries and pull stems using a straw, push from the bottom of the strawberry to pop the stem off the top.
  • Cut all strawberries in half and mix with the sugar, tapioca flour, salt, lemon juice and lemon zest ingredients, set aside. Keep the strawberry filling separate from the blueberry filling.

make the bottom crust, stripes, and stars

  • Prepare the bottom crust: On a cutting board, roll out pie crusts, lay them on the sprayed sheet pan and piece together all four of the pie crusts to form one bottom crust. Use a knife or pizza wheel to cut pieces and patch together a full crust gently pressing together and up the sides of the pan. Use a fork to poke small holes (aka docking) all over the bottom crust of the sheet pan, this helps the crust lay flat during the pre-bake (or blind-bake).  Sprinkle fine sugar on the bottom crust.
  • Use the 5th pie crust to cut the stars and stripes: Cut 25 small stars out with a 1" star cookie cutter. Using a clean ruler, lay it on the crust and use a knife or pizza wheel to cut 3 short stripes the width of the ruler and 9" long. Using a clean ruler, lay it on the crust and use a knife or pizza wheel to cut 3 long strips the width of the ruler and 16" long. Lay all the stars and stripes on the parchment lined baking sheet, and sprinkle with fine sugar.
  • If possible, re-chill your pie crusts in the fridge prior to baking on the sheet pans for an hour.  PRO TIP: Large sheet pans don't fit in my fridge, so I set the sheet pans on ice packs to keep them as cold as possible before baking. Pie crust bakes properly when very chilled going into a hot oven as it helps harden the fat in the butter and thus the pie dough, which helps the crust maintain its structure as it bakes.
  • Bake both the crust and the stars and stripes at 425 degrees for 15 minutes until the crusts are just turning golden brown. Pull both pie crusts out of the oven.  Leave oven on.
  • On the bottom pie crust, spread blueberry filling into the upper left corner in a small rectangle of the baked pie crust. Next, add the strawberry filling onto the pie. (Don't add the stars and stripes yet)
  • Bake at 425 for 25-30 minutes, until the berries are bubbling.
  • Remove pie from oven, and arrange the baked stars on top of the blueberries, add the 3 shorter stripes to the right of the blueberries, and the 3 longer stripes on the strawberries at the bottom of the pie.
  • Serve with whip cream and or ice cream! Enjoy...God Bless America!

Notes

Docking

Poking holes in pie dough, crackers, flatbread, or unbaked pastry are called docking. This technique helps the steam that builds up during baking escape, so the baked dough stays even and flat and doesn't puff up as it is baked. 

Preventing Soggy Pie Crust

No one wants a soggy bottom pie crust where the filling makes the crust all wet and gooey, yuck. Here is why it happens, and ideas to help you!.

Fruit

Use fresh, not overripe, fruit in baked pies. Overripe fruit releases a lot of water while baking. Use your ripe fruit in chilled pies.

Blind Baking

Blind baking helps the crust to bake evenly and keeps the crust from getting soggy by pre-baking without the filling.

Brush Blind-Baked Crust With Fruit Preserves

These can be brushed on the blind-baked pie crust to seal it from the fruit juices from the filling. Simply brush prebaked crust, and then add your filling before final baking.

Pie Filling Thickeners

Use a thickener, such as flour, cornstarch, potato starch, or tapioca flour. Baking fruit pies pulls water out of the fruit into the pie. Flour and cornstarch will help thicken the filling but makes cherry pie filling cloudy. Tapioca flour works well, although Tapioca small pearls, you can see little pearls in your filling, and I am not a fan of how that looks. Use potato starch for a clear filling. Corn starch needs to be heated in the filling in order to work as a pie thickener, it is a chemical reaction while cooking. 

Sugar On Pie Crust

By sprinkling sugar on pie crust, it does two things..one it sweetens the crust, and second, gives it a nice crunch. My Mom always finished her pies this way, and so do I. It is optional but really nice. 

Nutrition

Calories: 256kcal | Carbohydrates: 36g | Protein: 3g | Fat: 11g | Saturated Fat: 3g | Sodium: 189mg | Potassium: 140mg | Fiber: 2g | Sugar: 13g | Vitamin A: 15IU | Vitamin C: 36mg | Calcium: 18mg | Iron: 1.4mg