Go with the Grain: Rhubarb Custard Cake

When I walked through the farmer's market by my office a few weeks ago, nothing there piqued my interest except for the rhubarb. One of the vendors was selling bundled thin stalks of rhubarb that were bright red from root to tip. I had never seen such intensely colored rhubarb before and had to buy some.

I needed to make a dessert to bring to a colleague's Memorial Day barbecue and the "Rhubarb Custard Cake" from epicurious.com looked promising. Because all of the rhubarb is laid out on top of the cake in long pieces, I thought it would be a great way to showcase my beautiful red rhubarb. The recipe is meant to be baked in a 9-inch round pan but I doubled it and baked it in a 9-inch by 13-inch pan.

You mix this cake batter by hand. I whisked eggs and egg yolks with sugar until pale and thick; added melted butter, sour cream, rum, and lemon zest; and folded in the dry ingredients (flour, baking powder, and salt). I poured the batter into a parchment-lined pan and then trimmed the rhubarb so that each stalk was precisely the same length as the pan. I had enough rhubarb to cover the entire top of the cake with tightly-packed stalks and I sprinkled the rhubarb with some sanding sugar before putting the cake in the oven.
I always rotate cakes halfway through baking (unless it's a sponge cake like a genoise where opening the oven door might interfere with the rise of the cake), and when I turned this cake I was dismayed to see that all of the rhubarb had sunk underneath the batter -- or perhaps the cake had simply risen above the rhubarb, which I had wedged so tightly into the pan such that it might not have been free to rise with the batter underneath. [I also note that after I made this cake I recommended it my friend Louise, who ended up with a cake where all her rhubarb stayed on top. She mentioned a step in the recipe where you are supposed to chill the batter for 10 minutes to set it before adding the rhubarb. It was then I realized that the version of the recipe I relied on from epicurious.com doesn't include this chilling instruction, but the version of the recipe on the Bon Appétit website does. My lack of chilling wasn't the problem, however, because Louise said her batter set up nicely while the pan was just sitting on the counter while she cut her rhubarb.]

It was also difficult to tell when the cake was done, because wherever I stuck in a toothpick to test for doneness, it would go through a piece of rhubarb. (The recipe says the cake is done when it's golden on top and around the sides -- but how on earth are you supposed to be able to see the sides of the cake?) I crossed my fingers that the cake was done and let it cool completely before slicing.

Because I knew that all of the stalks of rhubarb inside the cake were laid in the same direction, I cut the cake into slender pieces about 3-inches by 1.5-inches, cutting along the grain of the rhubarb as much as possible. I was rewarded with gorgeous pieces of cake with an orderly stripe of bright red rhubarb running through the middle. The top surface of the cake had a crisp crackly texture from the sugar I had sprinkled on before baking.

I thought this cake was delicious. Even though the recipe says it should be stored at room temperature I kept it in the fridge because it was a little soft in the enter due to the moisture around the rhubarb. It tasted wonderful cold and had a pleasantly dense texture that was bordering on damp, without crossing the line to soggy. The flavor was bright from the lemon, and the cake had just the right level of sweetness to balance the tart rhubarb. The sweet crackly top was a wonderful feature.

Even though I was disappointed that my rhubarb sank into the cake, I was so pleased with the way it came out that I don't think I would change a thing -- and I wouldn't hesitate to make this cake again.

Recipe: "Rhubarb Custard Cake" from epicurious.com.

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Sally said…
Thanks for the recommendation! I LOVED this cake but should have paid more attention to lining w. parchment. I didn't use as much rhubarb as called for but then it really shrunk while baking so I should have. Mine did not sink. Just made this super easy cake and LOVED it -

https://www.bonappetit.com/recipe/raspberry-ricotta-cake
Yay! For all I know my rhubarb shrunk as well, but I might not have seen it, since it was inside the cake! That ricotta cake looks lovely, too -- thanks for the recommendation!