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Blueberry Rhubarb Slab Pie

  • Author: Erin Clarkson
  • Yield: Makes one 10" x 15" pie (approx 12 servings) 1x


Blueberry Rhubarb Slab Pie



Pie dough

  • 5 cups (620g) All-purpose flour
  • Pinch of Salt
  • 4 tsp (16g) sugar
  • 4 sticks (450g) cold butter, cut into cubes
  • 1 cup (240ml) cold water
  • 1 cup ice
  • ¼ cup (60ml) Apple cider vinegar


  • 1kg (2.2lbs) Fresh blueberries, washed and sorted
  • 500g (1.1lbs) Fresh Rhubarb, finely diced
  • 1 ½ cups (300g) raw sugar, plus more to sprinkle
  • ¼ c plus 2 Tbsp (50g) corn starch
  • ½ tsp salt
  • 1 tsp vanilla bean paste

Egg wash

  • 1 egg whisked with 1 Tbsp water



  1. Make the Pie dough in two batches. Combine the ice, water, and cider vinegar in a bowl and stir lightly to combine. Place 2 ½ cups flour, a pinch of salt, and 2 tsp sugar in a large bowl and stir lightly to combine. Cut 2 sticks (226g) butter into chunks, and add to the flour. Toss lightly to coat. Working quickly, using a pastry blender or  your fingers,  cut the butter into the flour mixture until there are only pea-sized chunks left. You want a few lumps of butter remaining to keep the pastry nice and tender.
  2. Sprinkle a few tablespoons of the ice water into the flour and butter mixture, and using a stiff spatula or your hands, mix in well. Continue adding water a tablespoon at a time ( I normally need about 8-10 tbsp) until you have a dough that holds together well, but is not too wet. Squeeze together with your fingertips to make a homogenous dough. Shape into a rectangle and wrap tightly in plastic wrap. 
  3. Repeat the process again. Place both rectangles of dough in the fridge to rest for at least two hours, or preferably overnight.


  1. Roll out one rectangle of dough on a lightly floured surface, until it is approximately ⅛" (3mm) thick. Carefully line a 10" x 15" pan with the dough. Trim excess, leaving approximately 1 inch overhang. Rest in the freezer while you Prepare the filling. 
  2. Place the Blueberries, rhubarb, sugar, corn starch, salt, and vanilla in a large bowl and toss to combine. Transfer to the prepared lined pan. Return to the freezer while you roll out the second rectangle of dough. Cut out your desired topping design - we did four three-strand braids to go around the edges of the pie, then used the rest of the dough to make stamped out shapes. Secure the braids, if using, to the edges of the pan using a little egg wash. Add the stamped out dough to the top of the pie in your desired pattern. Alternatively, top the pie with a lattice decoration of your choice. Trim any overhanging pie dough. Place the pie in the freezer to rest while you preheat the oven.


  1. Preheat the oven to 425˚f / 220˚c. Brush the top of the pie with egg wash, and sprinkle with additional raw sugar. Bake for 20 minutes, or until the pastry is set and beginning to go golden. Reduce the oven temperature to 375˚f / 190˚c, and bake for a further 40 to 45 minutes, or until the pastry is golden brown and the filling is bubbling. Remove from the oven and cool on a wire rack before cutting. Serve warm or at room temperature with ice cream or whipped cream.


Pie crust recipe from four and twenty blackbirds