Whenever I see the word rhubarb, I hear it in my sweet paternal grandmother’s voice. I don’t have a distinct recollection of her making a rhubarb dish, but she was a prolific pie and candy maker, so it’s certainly possible. To be honest, my memories of eating rhubarb growing up are few, vague and neutral. Eating it as an adult, I’ve loved it immensely and can clearly remember each instance of enjoying it. In spite of this, I’ve hardly made anything with rhubarb myself. Its season seems to slip by quickly each spring, and by the time I think of transforming it into a dessert, it’s gone from the market. Not this year.
Craving a casual dessert, I decided on a whoopie pie style cookie: soft but sturdy handheld cakes with a creamy filling. After cooking it on the stovetop, I incorporated rhubarb into both the cake batter and the center of the cookies, and I paired it with lightly sweetened cream cheese to mirror its tangy flavor. Some vanilla bean and good splash of spiced, dark rum would offer warmth and softness to balance out the tartness. (And this match was marvelous; I say rhubarb and rum belong together!) Here’s how I made them.
FOR THE RHUBARB:
- 1.5 pounds rhubarb, from about 3-6 stalks, depending on size
- 2/3 cup sugar
Rinse rhubarb; trim and discard tough ends. Cut each stem in half lengthwise, then cut horizontally in 1/2″ segments. You should have around 4 cups (approximately 1 lb, 5 oz.) chopped rhubarb, loosely packed. Place it in a medium saucepan and toss with sugar. Place pan over medium heat. Once sizzling, turn heat to medium-low, cover the pan, and cook for 10-15 minutes. Stop and stir it once after about 5 minutes. Keep an eye on the pan; it’s known to spill over. This usually happens when the rhubarb is quite juicy and done cooking; if yours spills over, check for softness and either remove from heat (if done) or reduce heat and cook a little longer. When done, rhubarb should be very soft and juicy — easy to mash. If it’s not, keep cooking in 5 minute increments and/or increase heat if needed.
Remove pan from heat, remove lid, and let rhubarb sit in the open pan until it reaches room temperature or at least lukewarm. Measure out a full 1/2 cup of cooked rhubarb and place it in a bowl. Mash it with a fork until an even pulp is formed (this will only take a minute or two, since the cooked rhubarb is so tender); set aside. Place remaining rhubarb in a non-reactive sieve or strainer over a bowl. Set aside.
FOR THE BATTER:
- 1/2 cup butter, softened
- 3/4 cup sugar
- 2 medium/large eggs
- seeds scraped from 1 large vanilla bean, or 1/2 teaspoon vanilla bean paste or powder
- 1.5 cups flour
- 1/2 teaspoon salt
- 1 teaspoon baking powder
- 2 tablespoons dark/spiced rum**
- the fork-mashed rhubarb from above
Preheat oven to 350 F. Line baking sheets with parchment; set aside. In a large bowl, cream the butter and sugar. Add the eggs one at a time, beating well after each addition. Scrape insides of bowl with spatula, add the vanilla bean, and beat until evenly dispersed. Over the butter mixture, sift the flour, salt, and baking powder. Begin to mix; batter will be quite thick. Gradually add the mashed rhubarb and the rum, mixing until they are evenly dispersed a smooth batter is formed; scrape sides of bowl as needed.
Scoop batter by heaping tablespoons onto lined cookie sheets, keeping 2″ space between dollops. You should have about 32 cookies. Bake 10 minutes, or until very edges of cookies are just beginning to look toasty, tops are dry to the touch, and bottoms are golden brown. Remove from oven; let cool completely on cookie sheets. They may flatten a bit as they cool. If not filling the same day, store covered up to 24 hours.
FOR THE FILLING & ASSEMBLY:
- 12 ounces cream cheese, softened well
- 1/3 cup powdered sugar, plus extra for serving (optional)
- 1/4 teaspoon salt
- 1 tablespoon + 1 teaspoon dark/spiced rum
- strained rhubarb from above (set aside its juice/syrup to use as you wish)
Beat cream cheese until smooth and soft. Sift the powdered sugar and salt over it. Beat until smooth, stopping to scrape bowl with spatula. Add the rum and beat until incorporated. (Note: This mixture is intentionally not too sweet, as the cookies and rhubarb are already sweetened. This recipe will likely leave you with a small amount of extra filling; it’s dreamy on toast or used as frosting.) Store filling covered in the fridge until ready to assemble the cookies (up to 24 hours).
To assemble, turn half of the cookies over and top with a rounded tablespoon of cream cheese filling. Add a heaping teaspoon of the strained rhubarb. If you want the rhubarb to show/ooze from the sides of the cookie sandwiches, spread filling gently to the edges with the back of a spoon. Top with a remaining cookie, right side up, and press down gently. If desired, sprinkle with sifted powdered sugar, and serve in paper cupcake liners. Rhubarb rum cakes are best when assembled just before eaten, but you can keep them covered and chilled, eating within 12 hours. The sprinkling of powdered sugar and the rhubarb will soak into the cookies after much longer than that, but they’ll still taste great up to 48 hours.
Creamy, tangy, and warm in flavor, these whoopie pie style cookies offer vibrancy both to the palate and to the eye. The tartness of the rhubarb, the richness of the filling, and the kick of the rum together make for an utterly tasty trio. Hearty and decadent, a rhubarb rum sandwich cake is perfect as a stand alone dessert or snack. And whether or not grandma would have made these, I trust she would applaud after her first bite. After all, a sweet, scrumptious, seasonal treat like this is practically irresistible.
Maybe next time… I wanted to let the rhubarb, vanilla and rum shine without distraction in this recipe, but I’m sure brown sugar in place of white, and/or the addition of some cinnamon or other sweet spices would likely taste wondrous alongside them. For do-aheads, as I mentioned above, feel free to make the cookies up to 24 hours in advance (refrigerate the remaining cooked rhubarb in a covered non-reactive container) , as well as the cream cheese filling. I find it best to let the components come to room temperature and to assemble the sandwiches as close to eating as possible.
**For a stronger rum flavor, lightly brush the bottoms of the cakes with rum before assembling, and/or add another 2 teaspoons rum to the filling. If you don’t want to use alcohol, skip it in the filling, and trade it for milk or a not-too-sweet juice in the batter.
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