Place the pie crust into the pie plate and flute the edges.
Take the diced rhubarb and place it in the pie plate.
In a medium bowl, add the eggs and whisk.
Add the milk, vanilla, and whisk again.
Add the flour, cardamon and sugar into the bowl and mix well.
Pour the custard mixture over the rhubarb and spread with a spatula so it’s even.
Bake in a preheated 375-degree oven for 45-60 minutes. Until the pie is set. If the middle of the pie is still jiggly that is ok, it will finish cooking while the pie cools.
Fully cool the pie and then serve plain or with whipped topping or ice cream.