Crustless Rhubarb Custard Pie

3 C rhubarb (diced)
1/3 C flour
3/4 C granulated sugar
1/2 tsp baking powder
1/2 tsp salt
4 large eggs
1 T vanilla extract
1 C milk
1 tsp butter (softened, used to grease the pie plate)

Preheat oven to 375 degrees. Clean and dice rhubarb. Very generously spread the softened butter on the bottom and sides of the pie plate. Add the diced rhubarb. Mix the remaining ingredients in a blender until well blended, one or two minutes. Pour that mixture over rhubarb. Bake for 40 minutes at 375 degrees. When done, the center will be ever so slightly jiggly. That will firm up once removed from the oven and let sit for 10 to 15 minutes.