Make a classic Rhubarb Pie with a flaky double crust and tangy-sweet filling — easy steps for a seasonal favorite.
Preheat the oven to 425°F so it's ready when the pie is assembled. This initial blast of heat helps set the crust quickly and encourages a flaky rise—so get that oven warm while you work, and have your 9-inch pie plate and rolling surface prepared nearby.
Roll one half of the double pie crust to about 1/8-inch thickness on a lightly floured surface and gently ease it into a 9-inch pie plate so it sits snugly with a slight overhang. Scatter a small mixture of 1 tablespoon granulated sugar and 1 tablespoon all-purpose flour across the bottom of the lined crust; this thin layer helps absorb extra juices and keeps the bottom crust from getting soggy.
In a large mixing bowl toss 6 cups of rhubarb (trimmed and cut into ½-inch pieces) with 1 cup granulated sugar, 6 tablespoons all-purpose flour (reserve a little for dusting if needed), and ½ teaspoon cinnamon. Mix until the pieces are evenly coated and the sugar begins to draw out the rhubarb’s juices—what you want is a glossy, slightly saucy pile of ruby-red chunks with a light dusting of flour binding the sweetness to the fruit.
Spoon the rhubarb mixture into the prepared bottom crust so the filling mounds slightly but is level with the rim. Roll the remaining crust to the same thickness, then place it over the filling — either cut into strips for a woven lattice or leave whole and cut slits for ventilation. Crimp the edges to seal, tidy the rim, and brush away any excess flour. The assembled, unbaked pie should look taut with visible ruby filling peeking through any lattice or slits.

Bake the assembled pie on the bottom rack of the oven for 15 minutes at 425°F to jump-start browning, then reduce the oven temperature to 350°F and continue baking for 40–50 minutes more until the filling is bubbling through the vents and the crust is a deep golden brown. The visual cues are important: deep golden edges and glossy bubbling filling mean the sugars and rhubarb have concentrated and thickened properly.
Remove the pie and let it cool on a wire rack for about 2 hours; cooling lets the filling set so slices hold their shape. When ready to serve, cut a generous wedge and plate it. A warm slice benefits from a scoop of creamy vanilla ice cream that softens against the hot filling, with a few small pieces of fresh rhubarb scattered as garnish for a bright, fresh note.
