Rhubarb Pie with Oat Streusel

Rhubarb Pie Ingredients

These are the 10 ingredients that you’ll need to make this rhubarb pie:

• All-purpose flour – Gives the streusel structure so it bakes into crispy clumps.
• Old-fashioned rolled oats – Add chew and nuttiness and create that rustic, crumble-style topping.
• Light brown sugar – Sweetens the topping and adds a caramel note.
• Unsalted butter – The fat that helps the streusel crisp and brown. Make sure to keep the butter cold so that you’ll get chunky, bakery-style crumbs.
• Kosher salt – Balances the sweetness and makes the flavors pop.
• Pie crust – Use my all-butter crust or your favorite. It needs to be sturdy enough to hold a tall, juicy filling.
• Rhubarb – The star of the show! Small, diced pieces cook evenly and give that jammy texture.
• Granulated sugar – Sweetens the tart rhubarb while still keeping that classic tang.
• Instant tapioca – Thickens the juices so the pie slices cleanly instead of running everywhere. You can also use cornstarch if you prefer that, but I think that instant tapioca bakes so well.
• Fresh orange juice – Rhubarb and orange go so well together. It brightens the flavor and adds a subtle citrus note that lifts the rhubarb.

The full amount of each ingredient can be found in the recipe card below.

How to Make Rhubarb Pie

The steps to make this pie are super simple, especially once the pie crust is formed and ready to go:

Make the streusel – In a bowl, combine the flour, oats, brown sugar, and salt. Cut the cold butter into ¼-inch pieces, add to the bowl, and work it in with your fingers or a pastry cutter until only pea-sized pieces remain. Chill while you prepare the filling.

Mix the filling – In a large mixing bowl, add the chopped rhubarb, sugar, instant tapioca, orange juice, and salt. Toss until evenly mixed.

Fill the crust – Place your prepared, chilled pie crust in a 9-inch pie dish. Pour the rhubarb mixture into the chilled, prepared 9-inch pie shell. The pie will look very full, which is what you want; rhubarb cooks down a lot. Sprinkle the chilled streusel evenly over the rhubarb, pressing lightly so it clings but still stays craggy on top. Set the pie on a parchment-lined baking sheet to catch any drips.

Bake – Bake the pie in a preheated 400°F oven for 10 minutes. Then reduce the oven temperature to 375°F and continue baking until the streusel is deep golden and the filling is bubbling all the way toward the center, about 70-80 minutes.

Cool completely – Remove the pie from the oven and let it cool on a rack for at least 4 hours. The filling will thicken as it cools. Once fully set, use a sharp or serrated knife to cut slices.

Recipe Tips

• Prep the rhubarb well – Wash the stalks well, pat them dry, and trim off any leaves or rough ends. Chop into ¼-inch pieces so they soften evenly in the oven.
• Bake on a sheet pan – This is a big, thick pie! A parchment-lined baking sheet under the pie saves your oven from sticky drips and makes cleanup easy.
• Let the bubbles guide you – Do not pull the pie out too early. You want to see the filling bubbling in the center, not just around the edges, so the thickener is fully activated.
• Protect the crust if needed – If your crust is browning before the filling is ready, loosely cover the edges with foil or a pie shield and continue baking until the filling bubbles.
• Cool for clean slices – Four hours of cooling feels long, but it gives the filling time to set. If you cut too soon, the pie will taste great but look messy.

More Pie Recipes

• Classic apple pie
• Oatmeal nut pie
• Easy blueberry galette
• Classic pumpkin pie
• Blueberry pie with streusel topping
• Peach blackberry pie
• Sour cream raisin pie