1Large egg, lightly beaten with a splash of milk or water
Demerara sugar, for sprinkling on top
In the bowl of a stand mixer combine the flour, salt and cubes of butter. Mix until the butter is pea-sized, 2-3 minutes. Slowly pour in the ice cold water. Mix until a dough starts to form and pulls away from the sides of the bowl. Adjust the amount of water needed, add more or less as needed. Form the dough into a ball and chill for 30 minutes.
Preheat oven to 375 degrees F and line baking sheet with parchment paper.
Place sliced rhubarb in a large bowl. Add sugar, cornstarch, cinnamon, nutmeg, salt, lemon juice, and vanilla. Mix well until combined.
Roll out the chilled pie dough to roughly an 11" disc and place on parchment lined baking sheet. Place the rhubarb mixture in the middle of the pie crust leaving a 2" border. Fold dough over and pinch to enclose the rhubarb, leaving the center exposed.
Brush the crust with egg wash and sprinkle the entire gallette with coarse sugar, focusing on the crust. Chill again for 10-15 minutes.
Bake at 375 degrees F, for 35-40 minutes, until crust is golden and juices are bubbling. Cool slightly before serving, serve sliced warm or at room temperature.
All images & content are the sole property of The Hearty Life. Please obtain permission prior to using my images. If you would like to republish a recipe, please link back to this post and re-write the instructions in your own words.