This recipe is adapted from one of the best Martha Stewart recipes I’ve ever come across. I’ve got a few variations, but you can find a link to the original recipe at the end of this post.
For the Topping
- 4 tablespoons unsalted butter, melted
- 1/2 cup all-purpose flour
- 1/4 cup sugar
- 1/4 teaspoon coarse salt
For the Cake
- 1 1/2 sticks unsalted butter (1 stick goes into batter, 1/2 stick goes under rhubarb in pan)
- 1 pound rhubarb, trimmed and cut diagonal about 1/2 inch thick
- 1 3/4 cups sugar (3/4 cup over rhubarb and 1 cup in cake batter)
- 1 1/2 cups all-purpose flour
- 1 1/2 teaspoons baking powder
- 1 1/2 teaspoons coarse salt
- 1/2 teaspoon finely grated orange zest plus 1 tablespoon fresh orange juice (optional)
- 2 large eggs
- 1 cup sour cream
Preheat oven to 350 degrees. Make the topping: Stir together butter, flour, sugar, and 1/4 teaspoon salt until moist and crumbly. I like to throw this into my mini chopper if using cold butter.
Make the cake: Grease a 9-inch round cake pan (2 inches deep). Place 4 tablespoons butter cut into pieces into the bottom of the pan. Toss rhubarb with 3/4 cup sugar and spread in bottom of pan over butter.
Mix your cake batter: Whisk together dry ingredients which are flour, baking powder, and 1 1/2 teaspoons salt. In stand mixer, beat one stick butter and one cup sugar on medium speed until pale and fluffy. Beat in zest and juice. (I rarely have oranges in the house, so I add one tablespoon of lemon juice instead.) Beat in eggs, one at a time, until incorporated, scraping down sides of bowl. Beat in flour mixture in three additions, alternating with sour cream, until smooth. Spread evenly over rhubarb. Crumble topping evenly over batter.
Bake until a toothpick inserted into the batter in the center comes out clean and top springs back when touched, about 1 hour to 1 hour and fifteen minutes. Let cool for 10 minutes. Run a knife around edge of cake, and invert onto a large plate. It will be very juicy unless you have a leaky spring form pan like I do! Let cool completely if you like to serve with whipped cream.
Note: I have been making this recipe in a spring form pan the past few years to make it easier to get out. Sometimes I flip it over, but not all the time. We have made this over the campfire in the dutch oven many times. A show stopper for sure!
Link to original recipe: http://www.marthastewart.com/344240/rhubarb-upside-down-cake