Sweet Potato and Rye Coffee Cake
/The very best buttermilk coffee cake recipe, filled with sweet potatoes and fall spices, topped with a ginger crumble topping and drizzled with a browned butter glaze.
Guys, this sweet potato and rye coffee cake is SO GOOD. I often have a never ending list in my mind (and jotted down in sticky notebooks or on loose pieces of paper) of recipes that I want to develop. Sometimes they come from a photo I saw or a meal I ate, other times they just pop into my head seemingly out of nowhere. As I create content, I try to move through this list, and sometimes, a recipe idea will hang out on my list for months, while other times, I head to the kitchen and make it immediately. Which is really not fair to those long-standing little guys, like ricotta donuts, that have been hanging out on my to-do list since March, but such is life. Anyway, this sweet potato coffee cake was in the latter category. One day a couple of weeks ago, the idea popped into my head and I made it the next day. It was perfect the first time. I jotted down notes, photographed it, sent the leftovers with my husband to work and set out on the next project. But then my husband came home and some of his co-workers loved this cake so much that they wanted to special order one. So I made another. Then they special ordered another one. So I made it again. And again. Now over the last three weeks, it feels like this is the only cake I’ve baked. If that’s not a glowing review for this cake, I don’t know what is. Go make it today so I don’t have to anymore!
about the coffee cake
This is a creaming method cake, that uses solid fat (butter) so that it has a light, fluffy consistency, but, there’s a little bit of a secret weapon in the form of buttermilk. Buttermilk provides fat and moisture while also tenderizing the cake, making it ultra-moist and a little dense (like an oil-based cake). That means that this final cake is BOTH light and dense, fluffy and moist. It’s everything to everyone and I love it. The addition of rye flour gives a bit of a nutty, tangy flavor, but you could easily use 100% all-purpose flour if that’s what you had on hand. Spelt would also be a fun addition if you were feeling experimental.
I like to roast my sweet potatoes the day before so they have time to cool completely before I peel and mash them (see notes below the recipe), just make sure that everything is room temperature before mixing. This cake is a little sensitive and has a tendency to curdle up a bit if any ingredient is even a little bit too cold. If your batter does curdle, especially after adding the eggs and the sweet potato, all is not lost, just add a little of your dry ingredients. The starches will help bind everything back together.
And don’t forget the browned butter glaze, the real MVP of this whole thing. You’ll want to eat it with a spoon and I will not judge you one bit if you do.
Sweet Potato and Rye Coffee Cake
Ingredients
- 1/2 cup (65 g) rye flour
- 3/4 cup (75 g) rolled oats
- 1/2 cup (100 g) brown sugar
- 1/2 tsp ground cinnamon
- 1/2” piece of fresh ginger, grated (or 1/2 tsp ground ginger)
- 1/2 tsp kosher salt
- 1/2 cup (113 g) unsalted butter, softened
- 1 1/2 cup (190 g) all purpose flour
- 3/4 cup (100 g) rye flour
- 1/2 tsp baking powder
- 1/2 tsp baking soda
- 3/4 tsp kosher salt
- 1/2 tsp ground cinnamon
- 1/4 tsp ground cardamom
- 1/4 tsp ground nutmeg
- 1/4 tsp ground ginger
- 3/4 cup (170 g) unsalted butter, softened
- 1 cup (220 g) granulated sugar
- 1/2 cup (100 g) brown sugar
- 3 eggs, at room temperature
- 2 tsp vanilla extract
- 3/4 cup (150 g) sweet potato, cooked and mashed*
- 1 cup (242 g) buttermilk, at room temperature
- 1/2 cup (113 g) unsalted butter
- 1 1/2-2 cups powdered sugar
- pinch of salt
- about 1/4 cup heavy whipping cream*
Instructions
- In a medium bowl, whisk together flour, oats, brown sugar, cinnamon, ginger, and salt.
- Add butter and work together using your fingers until butter is completely mixed in and no dry spots remain. Place the crumble in the refrigerator to chill while you make the rest of the cake.
- Preheat oven to 350°F and line a 9x13” baking dish with parchment paper.
- In the bowl of a stand mixer fitted with the paddle attachment, combine butter, granulated sugar, and brown sugar. Beat on medium speed until light and fluffy, about 2 minutes, making sure to scrape down the sides and ensure all butter chunks are mixed in.
- Meanwhile, in a medium bowl, whisk together flour, rye flour, baking powder, baking soda, salt, cinnamon, cardamom, nutmeg, and ginger. Set aside.
- With the mixer on low speed, add eggs one at a time, mixing each completely before adding the next. Scrape down the sides of the bowl and then add mashed sweet potato and vanilla extract. Mix on low-medium speed for 1-2 minutes more, until everything is combined and homogenous.
- With the mixer on low-speed, add 1/3 of the dry ingredients, followed by half of the buttermilk. When the buttermilk has mixed in, add another 1/3 of the dry ingredients, followed by the remaining half of buttermilk, then the remaining 1/3 of the dry ingredients. Scrape down the sides of the bowl and then mix one more minute. Remove bowl from mixer and use a rubber spatula to gently fold the batter a few more times, ensuring that the batter is smooth and homogenous and everything is well combined.
- Pour batter into prepared baking dish and use an offset spatula to smooth into an even layer. Remove crumble from refrigerator and sprinkle evenly over the top of the cake.
- Bake for 45-50 minutes, rotating the pan halfway through the baking time, until a cake tester or toothpick comes out clean when inserted into the center of the cake. Let cool completely in the pan while you make the glaze.
- Place butter in a small saucepan set over medium heat and cook for 6-7 minutes, swirling occasionally, until butter is foamy and fragrant and small amber flecks appear on the bottom of the pan.
- Quickly remove the butter from the heat and pour into a heatproof bowl. Immediately whisk in powdered sugar, salt, and heavy cream, adding more heavy cream if needed to achieve your desired consistency. Drizzle glaze over coffee cake and let set before slicing.
Notes:
on sweet potatoes: For this recipe, sweet potatoes need to be soft and mashable. I like to poke holes in a whole sweet potato and then roast it in a 400° F oven for 30-40 minutes until soft. I let it cool completely (sometimes even just pop it in the fridge overnight) and then peel it cold.
for the glaze: About 1/4 cup of heavy cream is a very vague measurement and for that I am sorry, but I’ve made this recipe many times and I think I use a slightly different amount every time. I would recommend starting with 3-4 tbsp of heavy cream and adding more if needed to loosen the glaze. If your glaze begins to separate and become oily, just add a little more heavy cream and keep whisking. The fat in the cream should help it emulsify and come back together. If you get a little heavy handed and your glaze is too runny, add a little more powdered sugar- it’s very forgiving!
