A Quick Slow Cook Pays Off: Rhubarb Coffee Cake with Browned Butter Streusel

Last year, I supported Nicole Rucker's Kickstarter campaign to fund her Fat & Flour Bakery in the Los Angeles Grand Central Market. The campaign took place in March 2020, in very early pandemic days, and I am so impressed that she was able to bring the project to fruition. My reward for backing the project included a copy of Rucker's cookbook Dappled. But it was almost winter when the cookbook arrived, and because the recipes are focused on fruit, I set the book aside for later. To be fair, the recipes are not limited to summer fruits -- but I don't have enough room for all of my cookbooks, so I stashed it in the guest bedroom until summer fruit season.

The first recipe I tried from the cookbook was the "Rhubarb Coffee Cake with Browned Butter Streusel," because I had purchased some beautiful rhubarb at the farmers market. (Actually, I had also purchased rhubarb earlier in the season, but it was while our oven was broken and I for some reason had completely forgotten that critical fact. I turned it into Edd Kimber's Rhubarb and Star Anise Sorbet.)

There are three components in this cake: browned-butter streusel; slow-cooked rhubarb; and cake. First I made the rhubarb. While calling something "slow-cooked" might make you assume the process could take hours, the rhubarb requires fewer than 20 minutes of active time. You simply cook sugar with water and vanilla bean paste until the sugar melts; add chunks of rhubarb; cook until the rhubarb is softened; and cool. The streusel is a mixture of browned butter (cooled until it's almost room temperature), sugar, flour, and salt. 

To make the cake batter, you beat room temperature butter with sugar and kosher salt until light and fluffy; add eggs; mix in Greek yogurt (I didn't have any and used sour cream instead), vanilla, and candied orange zest (which I also didn't have, so I used crystallized ginger instead); and incorporate the dry ingredients (flour, baking powder, and baking soda). You're supposed to bake the cake in a 9-inch by 13-inch pan, but I divided it between two greased and parchment-lined 9-inch round pans; I often think that fruit-based cakes seem more elegant when served in pie-shaped wedges instead of squares. In each pan I arranged layers of cake batter, rhubarb, more cake batter, more rhubarb, and then finally the streusel.

My cakes look nothing like the photos in the cookbook, and I don't just mean the difference in shape. The cake in the cookbook is covered in which looks like a thick, chunky layer of streusel that is nearly contiguous, with very little fruit visible. By contrast, my streusel layer was considerably thinner and more sparse, with lots of pink rhubarb was peeking though (and there's less than a 10% difference in volume between two 9-inch round pans and a single 13-inch by 9-inch pan, so my pan selection shouldn't have significantly affected the thickness of the streusel). I didn't strain the brown butter, so you could see black flecks of milk solids in the streusel. I thought they resembled black pepper.

 

This cake was so delicious. While I do bake a fair amount with rhubarb, I don't actually love the tart flavor. But the generous amount of slow-cooked rhubarb in this cake was mellow and sweet with no trace of astringency. This is definitely one of my favorite rhubarb cakes. And the addition of the crystallized ginger was so good. I loved everything about this cake, and somehow the cake held up without becoming soggy. I would make it again in a heartbeat.

 

Recipe: "Rhubarb Coffee Cake with Browned Butter Streusel" from Dappled by Nicole Rucker.