Rhubarb Upside-Down Cake
This cake has a crumb "topping" that actually ends up on the bottom. Each bite has a surprisingly crunchy texture.
For the Topping
- 4 tablespoons unsalted butter, melted
- 1/2 cup all-purpose flour
- 1/4 cup sugar
- Coarse salt
For the Cake
- 1 1/2 sticks unsalted butter, room temperature, plus more for buttering pan
- 1 pound rhubarb, trimmed and cut on a very sharp diagonal about 1/2 inch thick
- 1 3/4 cups sugar
- 1 1/2 cups all-purpose flour
- 1 1/2 teaspoons baking powder
- Coarse salt
- 1/2 teaspoon finely grated orange zest plus 1 tablespoon fresh orange juice
- 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.
Make the cake: Butter a 9-inch round cake pan (2 inches deep). Dot with 4 tablespoons butter (cut into pieces). Toss rhubarb with 3/4 cup sugar; let stand for 2 minutes. Toss again, and spread in pan.
Whisk together flour, baking powder, and 1 1/2 teaspoons salt. Beat remaining stick butter and cup sugar with a mixer on medium speed until pale and fluffy. Beat in zest and juice. Beat in eggs, 1 at a time, until incorporated, scraping down sides of bowl. Beat in flour mixture in 3 additions, alternating with sour cream, until smooth. Spread evenly over rhubarb. Crumble topping evenly over batter.
Bake until a toothpick inserted into the center comes out clean and top springs back when touched, about 1 hour. Let cool for 10 minutes. Run a knife around edge of cake, and invert onto a wire rack. Let cool completely.