It always makes me so happy after a long winter to see little green nubbins of rhubarb leaves poking up through the soil in my garden. My hardy little rhubarb plant can always be counted on to spring to life before any other plants or bulbs have sprouted. I’ve learned that rhubarb is one of those plants that people either love or hate: If you do not have one at home in your garden, you covet others’ rhubarb patch and wince every time you have to purchase rhubarb stalks at the store for $5.99/lb. If you do have rhubarb in your garden, you rue the fact that it grows like a weed and practically crowds out every other living thing within 5 feet of it, and that it’s difficult to get rid of. Yet, we are all still captivated by the tart and unusual taste of this plant, and look for ways to turn it into something delicious in our kitchen.
My love for rhubarb began when I was a little girl. My grandparents often came to our house for dinner, and in the spring and summer, my grandma Dotty would bring a fresh batch of homemade rhubarb sauce. It was always slightly different, and made up of whatever she had on hand in the kitchen the day she made it, but it typically included fresh rhubarb, sugar, a little bit of Jell-O® gelatin (strawberry, cherry or raspberry flavors work best!), and juice or water. Those ingredients, when boiled together, make a lovely pink soupy sauce that is good on just about anything: vanilla ice cream, granola, cake, Greek yogurt, etc. It’s also delicious on its own in a bowl with a splash of cream or half and half on top. I have my grandma to thank for instilling this love of rhubarb in me at a young age. (She still remembers how much I like it, and in fact gave me a cookbook last year from the annual Rhubarb Festival—definitely worth checking out!) I’ve always been fascinated, too, by the fact that a plant can have poisonous leaves, yet edible stalks. (Rhubarb leaves contain oxalic acid, which is toxic to humans and pets when eaten!)
As an adult, I’ve tried to share my affinity for rhubarb with friends who didn’t necessarily grow up eating it and are perhaps intimidated by it. Once, I hosted a rhubarb-themed dinner party at my house, where the offerings ranged from rhubarb-glazed grilled chicken to rhubarb chutney on lamb chops, rhubarb bars, rhubarb cocktails, rhubarb cookies and pie, and even homemade rhubarb ice cream. I think my friends thought I was a little crazy, but they still devoured it all.
My latest rhubarb fascination has been with rhubarb streusel cake. It all began in Vienna, Austria, in a famous coffeehouse called Demel. I was studying abroad for graduate school at the time, and had a day off, in which I excitedly explored (for the first time) what has since become one of my favorite cities in the world. Wien (Vienna) has established itself over the past several centuries as cultural mecca of sorts for music, architecture, history, dance, fashion, and of course, its’ food scene. In my humble opinion, Vienna is one of the most utterly sophisticated cities in the world, one worthy of a visit if you’ve never been. (see also: Salzburg, of Sound of Music fame, and the Tyrolean Alps for unparalleled mountain hiking!)
So I was strolling down the Kohlmarkt (an upscale street located in the 1st district or Innere Stadt of Wien), I suddenly spied a lovely looking sign for a coffee house (for which Vienna is famous). The name sounded vaguely familiar—Demel? I recalled a colleague mentioning it to me as a “must visit” shop. Perfect—I had practically wandered right to it! To set the scene properly, it was a lovely sunny day in mid-May. The imperial Hofburg Palace is about 50 yards away, and there were many elegant Viennese couples sitting outside at café tables enjoying coffee and pastries at this 250 year old establishment. It was calling my name, so I went inside!
This was the sight that greeted me as I entered:
Yes, great difficulty ensued from this point forward. I did not need to buy more than one treat, but I yearned to try EVERYTHING in the entire shop. Do I go for the French macaron? Oui. Or what about the Sacher Torte (which Vienna is famous for)? No; as I later came to find out, Sacher Torte is overrated (it’s quite dry). What about Schwarzwaldkirschtorte, a German specialty with cherries and chocolate:
As I read the diminutive signs in front of each delectable treat, the decision became increasingly more difficult. Finally, my eyes stopped on a pastry that was titled “Rhabarber-streuselkuchen”. The decision was a swift one. I left the shop with a dainty Demel box in hand, a slice of Rhubarb Streusel Cake tucked away inside. My first bite was taken as I rode the straβenbahn home that afternoon, and I realized that this cake was playing in an entirely different league than the desserts I was used to. Perhaps it was the cake’s egg-y, almost custard-like texture, or maybe it was the buttery brown sugar streusel crumbles obscuring the generous amount of very tart rhubarb hidden beneath, but it was utterly irresistible. I managed to make the slice last until morning.
This was 5 years ago, and I’ve long since been back in the US, having to deal with the harsh reality that Demel is not just down the street from where I live. Thus, I’ve taken to trying to recreate a decent version of this treat in my own kitchen. I will be the first to admit that this version is quite different—more of a hybrid of a rhubarb upside-down cake paired with the Demel streusel cake, but I find it to be quite delicious nonetheless. I hope you can find some fresh, crisp rhubarb this spring and try this recipe out! And while you’re enjoying this cake with a cup of strong espresso and dollop of cream (another Viennese coffee specialty, called an Einspänner), perhaps you can start planning out that trip to Austria…!
Upside-Down Streusel Cake
I love this served at room temperature or even chilled slightly. The rhubarb caramelizes at the bottom of the pan during baking, which offsets its tartness nicely, and the use of yogurt instead of sour cream lightens the cake up so it’s still moist but not too rich.
For the Crumble Topping
- 4 tablespoons unsalted butter, melted
- 1/2 cup all-purpose flour
- 1/4 cup brown sugar
- ½ cup chopped pecans
- ½ tsp coarse salt (preferably sea salt but kosher will work too)
For the Cake
- 1 1/2 sticks unsalted butter, room temperature, plus a bit more for buttering pan
- 1 1/4 pounds of rhubarb, cleaned and sliced into 2” long pieces. (If rhubarb is thick, slice down the center of the stalk once before slicing into 2” pieces)
- 3/4 cups powdered sugar
- 1 cup light brown sugar
- 1 1/2 cups all-purpose flour
- 1 1/2 teaspoons baking powder
- 1 teaspoon coarse salt (sea salt or kosher salt)
- 1/2 teaspoon finely grated grapefruit zest plus 1 tablespoon fresh grapefruit juice (Orange zest and juice may be substituted here in a pinch, but it really is nicer with grapefruit)
- 1 tsp pure vanilla extract
- 2 large eggs, room temperature
- 1 cup plain Greek yogurt
Preheat oven to 350 degrees F with a shelf in the upper third of the oven. In a small bowl, prepare the crumble topping: combine melted butter, flour, sugar, pecans and 1/4 teaspoon salt until moist and crumbly. Set aside.
Prepare the cake: Butter a 9-inch round cake pan. Cut 4 Tbsp of butter into small pieces and scatter them across the bottom of the greased pan(s). A nonstick round pan is ideal, but natural will work too. Do not use parchment paper.Toss rhubarb with 3/4 cup powdered sugar; let stand for 2 minutes. Toss again, and spread in pan(s) on top of butter dots. If there is juice at the bottom of the bowl, be sure to pour that in, too.
Cream remaining stick butter and cup of brown sugar with a mixer on medium speed until fluffy, about 3 minutes. Beat in zest, juice, and vanilla. Beat in eggs, 1 at a time, until incorporated, scraping down sides of bowl. Add baking powder and salt, mixing thoroughly. Beat in flour in 3 additions, alternating with plain yogurt, until smooth. Do not overmix!
Spread mixture evenly over rhubarb in the prepared pan. Scatter the 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 for a 9” round pan. Let cool for just 10 minutes or sugars will solidify and cake will not release from pan.
Run a knife around edge of the cake pan, and invert onto a wire rack or serving plate. May be served warm or cold, depending on preference.