3cupsfresh or thawed frozen rhubarb, or thawed frozen rhubarb, cut into 1/2-inch pieces
1Tablespoonunsalted butter, at room temperature, for the pan
1/4cupwhite sugar, for the pan
For the cake batter:
1 1/2cupsall purpose flour
2 1/2teaspoonbaking powder
1/2teaspoonsalt, reduce to 1/4 tsp if using salted butter
2/3cupunsalted butter, at room temperature
Icing/confectioners' sugar, for garnish, optional
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Preheat oven to 350F. *Reduce temperature to 325F if using a glass pan.
*For frozen rhubarb, thaw in a colander to allow excess moisture to drain off, then pat dry well. Don't squeeze the rhubarb at any point, so it will retain its shape.
Prepare a 9-inch round cake pan by coating both the bottom and sides with softened butter. (You can also use a deep dish pie plate or similar diameter. Note that an 8-inch pan will almost certainly be too small to hold all the batter.) Sprinkle white sugar evenly over the bottom of the pan.
Add the diced rhubarb to a large bowl. Microwave the jam for 30 seconds to thin it, then pour over the rhubarb. Stir to coat the rhubarb well in the jam. Pour the rhubarb mixture into the pan, spreading into an even layer. Set aside.
Make the cake batter: In a medium bowl, whisk together the flour, baking powder, cinnamon and salt. Set aside.
In a large bowl with an electric mixer or the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar at medium speed until lightened, about 2 minutes. Beat in the eggs, one at a time, beating well between additions and be sure to scrape the bowl, as needed. Add the vanilla and mix in.
With mixer on low, add 1/3 of the flour mixture, followed by 1/2 of the milk. Add another 1/3 of the flour mixture, the remaining milk, then the remaining flour. Mix just until combined.
Spoon batter over-top of rhubarb in pan and spread out to an even layer.
Place cake pan on top of a baking sheet (just in case!).
Bake for 40-50 minutes, or until the cake tests clean (be sure to test just the cake part and don't test too far down so that you hit the rhubarb layer). The cake should be quite golden.
Remover from the oven and allow to stand in the pan for 5 minutes. Run a knife around the edges of the pan, then place a large plate over-top of the cake pan. Invert the cake onto the plate.
Serve warm, garnished with a dusting of icing sugar and/or a dollop of sweetened whipped cream or vanilla ice cream.
This rhubarb cake is best enjoyed on the day it is baked, but will keep pretty well covered on the counter for 2-3 days.Be sure to read the information above this recipe card for more tips on making this recipe!