Preheat oven to 375°F (190°C).
Place the unbaked pie crust into a 9-inch pie dish and crimp the edges if desired.
Spread the chopped rhubarb evenly across the bottom of the crust.
In a medium mixing bowl, whisk together the sugar, eggs, cream, flour, vanilla extract, and salt until smooth.
Pour the custard mixture evenly over the rhubarb.
Drizzle the melted butter over the top of the filling.
Bake the pie for 45–50 minutes, or until the custard is set and the crust is golden brown.
Remove from the oven and allow the pie to cool for at least 1 hour before slicing.
Serve at room temperature or chilled with whipped cream or vanilla ice cream.