A simple custard base lets the sweet-tart flavor of spring shine through in the sugar-coated pieces of rhubarb.
Preheat oven to 375 degrees. On a clean work surface lightly dusted with flour, roll out pate brisee to an 11-inch round (about 1/8-inch thick). Transfer to a 9-inch pie plate, and trim edges of dough with kitchen shears to a 1/2-inch overhang. Fold edges under, and press to seal using the tines of a fork. Freeze until firm, about 20 minutes.
Line crust with parchment, leaving an overhang on all sides. Fill completely with pie weights, dried beans, or rice. Bake until bottom is dry, 20 to 25 minutes. Remove weights and parchment. Continue baking until bottom of crust is golden, 7 to 9 minutes more. Let cool.
In a bowl, toss rhubarb with 1/4 cup sugar. Let stand 10 minutes. In another bowl, whisk together flour, remaining 1 1/4 cup sugar, eggs, butter, and heavy cream until smooth and combined. Pour filling into crust. Scatter rhubarb evenly over top, gently pressing into custard. Bake until puffed and golden in places and slightly wobbly in the center, 50 minutes to 1 hour (tenting with foil if browning too quickly). Transfer to a wire rack; let cool 1 hour. Refrigerate until ready to serve, about 1 hour and up to 1 day.