The addition of buttermilk lends tanginess and richness to the cake batter, while the rhubarb is marinated in sugar before baking, softening the fibrous stalks to result in a deliciously jammy texture.
Frequently asked questions
Is rhubarb a fruit or a vegetable?
Rhubarb is classified as a perennial vegetable, but its tart flavor makes it a natural choice for treats like this rhubarb coffee cake. It's often coupled with strawberries, which peak around the same time in the spring to lend their juicy sweetness to the sour crimson stalks. By the time the summer heat kicks in, rhubarb will have become fat and woody, so take advantage of this unique veggie when it appears in the market (or your garden!) from late March to early June.
How do you prep rhubarb for this cake?
Justin Chapple trims off the ends, cuts any thicker stalks in half, and discards the leaves, since they're poisonous and not edible. Once that's done, he puts the stalks on a rimmed baking sheet and sprinkles them with granulated sugar, tossing the rhubarb so that it's evenly coated. Allowing the sugar to sit on the rhubarb for 20 to 30 minutes will not only help temper its tartness, but soften the stalks as well.
Notes from the Food & Wine Test Kitchen
Feel free to serve the cake either warm or cooled completely — pair it with a cup of coffee for a weekday breakfast or a glass of Champagne for a holiday brunch.
Ingredients
Streusel
-
3/4 cup all-purpose flour (about 3 1/4 ounces)
-
3/4 cup packed light brown sugar
-
1 teaspoon ground cinnamon
-
3/4 teaspoon kosher salt
-
6 tablespoons unsalted butter (3 ounces), chilled and cut into 1/2-inch pieces
Cake
-
1 1/2 pounds 10- to 12-inch-long rhubarb stalks (about 8 stalks), halved lengthwise if thick
-
1 3/4 cups granulated sugar, divided
-
2 1/2 cups all-purpose flour (about 10 5/8 ounces), plus more for dusting
-
1 teaspoon kosher salt
-
1 teaspoon baking powder
-
3/4 teaspoon baking soda
-
1/2 cup unsalted butter (4 ounces), at room temperature, plus more for greasing
-
2 large eggs
-
1 1/4 cups buttermilk
-
1 tablespoon vanilla extract
Directions
Make the streusel
-
Stir together flour, brown sugar, cinnamon, and salt in a medium bowl. Add butter; using fingers, work butter into flour mixture until completely incorporated and mixture clumps together. Cover and refrigerate until ready to use or up to overnight (12 hours).
Make the cake
-
Preheat oven to 350°F. Lightly grease a 9- x 13-inch baking pan or dish with butter. Dust pan with flour and shake out excess. Place rhubarb on a rimmed baking sheet and sprinkle with 1/4 cup granulated sugar; toss to coat. Let stand, tossing occasionally, until sugar is mostly dissolved, 20 to 30 minutes.
-
Whisk together flour, salt, baking powder, and baking soda in a medium bowl; set aside. Beat butter and remaining 1 1/2 cups granulated sugar with a stand mixer fitted with the paddle attachment on medium speed until light and fluffy, about 2 minutes, stopping to scrape down sides of bowl as needed. With mixer running on medium speed, add eggs, 1 at a time, beating well after each addition. Reduce mixer speed to low; beat in buttermilk and vanilla. With mixer running on low speed, gradually add flour mixture, beating until just incorporated, about 1 minute, stopping to scrape down sides of bowl as needed.
-
Transfer batter to prepared pan and spread evenly. Arrange rhubarb lengthwise in a single layer on top of batter. Sprinkle with streusel. Bake in preheated oven until a wooden pick inserted in center of cake comes out clean, 55 minutes to 1 hour and 5 minutes. Remove from oven; let cake cool in pan on a wire rack at least 20 minutes or up to 6 hours. Serve warm, or let cool completely.
![Rhubarb Coffee Cake](https://www.foodandwine.com/thmb/cEqMGyAJfpZ8o_i1iK1Cat8RRnY=/1500x0/filters:no_upscale():max_bytes(150000):strip_icc()/rhubarb-coffee-cake-FT-RECIPE0322-291015a5c81c464faaba21bb3a6c57d6.jpg)