There are three elements to this moist sour cream coffee cake-- a layer of caramelized rhubarb, a moist a layer of streusel. When the cake is inverted, the streusel becomes the crust. The rhubarb becomes tender with just the right balance of sweet and tart.
Course Cake, Dessert
Keyword coffee cake, Rhubarb Coffee Cake, Rhubarb Upside Down Cake, Upside Down Cake
Coarse saltif using table salt, decrease amount by half
CAKE:
1 1/2sticks unsalted butterroom temperature, plus more for buttering pan
1poundrhubarbtrimmed and cut on a very sharp diagonal about 1/2-inch thick
1 3/4cupssugar
1 1/2cupsall-purpose flour
1 1/2teaspoonsbaking powder
Coarse saltif using table salt, decrease amount by half
1/2teaspoonfinely grated orange zest plus I used lemon zest and lemon juice
1Tbspfresh orange juice
2large eggs
1cupsour cream
Instructions
Preheat oven to 350°F.
Topping:
Stir together butter, flour, sugar, and 1/2 teaspoon coarse (not table) salt until moist and crumbly.
Cake:
Butter a 9-inch round cake pan (3-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 coarse salt. (If using table salt, decrease amount by half.)
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.
Notes
Let the cake cool for 10 minutes before removing it from the pan. The rhubarb will be too hot to handle safely right after baking. But if the cake sits much longer, it may stick.NOTE: The cake pan size is important! I used a 9" cake pan with a 3" depth. Otherwise, you might risk your cake overflowing, so put a baking tray underneath!Please be aware that coarse (kosher) salt is different that table salt. I use coarse salt, unless otherwise notes. Use HALF the amount of table salt, if that is what you use.Recipe Source: Martha Stewart