Jammy Sour Cream Crumb Cake

With a golden, buttery crumb cake—made extra rich and tender with sour cream—topped with a swirl of bright fruit jam and a crisp, shortbread cookie-like crumb for crunchy contrast, this is a cake that’s as suitable for breakfast as it is for dessert (or even afternoon tea).

Sometimes simple cakes hit just as hard as any multi-tiered masterpiece. As is the case with this deceivingly simple crumb cake, with three layers of textural perfection: tender and buttery cake, sweet and sticky jam, and crunchy crumb topping. And did I mention it’s ready in under an hour from start to finish?

I always seem to have a few jars of homemade jam open and floating in the fridge at any given time. Such is the plight of the jam maker (as I’m sure anyone who makes homemade jam in any quantity likely has the same problem).

It’s why I have an entire category of recipes dedicated to Jams in Action: recipes that use jam as a component in one way or another.

That’s also why this cake—complete with its sticky swirl of sweet and fruity jam—is my ideal cake. One that’s buttery and rich but not overly sweet, with multiple textures to please the palette, and that also uses up some of those sad little orphan jams hidden away in the back corner of the fridge.

The recipe itself is quite similar to my grandma’s sour cream coffee cake (this version with apples being the first version I ever posted), with slightly tweaked proportions and an added shortbread-like crumb topping, plus a layer of fruit jam in between. I like to think of it as a choose-your-own-adventure cake, where the type of jam you use will make it taste completely different every time!

I’ve personally made it with plain raspberry jam, old-fashioned strawberry jam, as well as a blend of raspberry and guava jam from random leftover jars that I mixed together (this one was my favorite, the guava is so punchy I just love it). While I don’t have a recipe for raspberry guava jam, I do have a strawberry guava jam that I think would be absolutely lovely here!

While I’m not calling it coffee cake this time, it really is quite wonderful as a breakfast cake, especially when you take into account the fruity jam. But it’s also perfectly sweet and satisfying for an afternoon tea and even fancy enough to count as dessert (maybe dusted with powdered sugar and served with a scoop of ice cream, perhaps?)

Most recipes billed as sour cream crumb cakes are heavily spiced with cinnamon in the crumb; so much cinnamon, in fact, that the crumb takes on a noticeably brunette hue in contrast to the golden blonde of the cake.

I opted not to include cinnamon in this recipe, as I really wanted a fruit forward flavor and felt the cinnamon would overpower the jam. That said, feel free to add a bit of cinnamon to the crumb mixture if you’re looking for something more traditional (cinnamon does pair well with fruits like fig, apple, pear and plum, so maybe choose your jam accordingly).

Make the crumb topping by first combining flour, sugar, brown sugar and salt in a mixing bowl. Pour melted butter into bowl with dry ingredients. Mix until the crumb mixture comes together in to a crumbly dough; it should stick together when pressed between your fingers. To make the cake batter, in a mixing bowl, cream butter and sugar together until fluffy, then add in egg. Add baking soda to sour cream; wait until right before you need it, and don’t do this too far ahead of time. After about 30 seconds the sour cream will turn noticably foamy. Add half of dry ingredients to the mixing bowl. Add half of foamy sour cream mixture along with milk and extracts, mixing until just incorporated. Repeat with the second half of dry ingredients and remaining sour cream. Dump finished cake batter into a square baking pan lined with parchment paper. Spread batter evenly into the cake pan using an offset spatula. Drop dollops of fruit jam of your choice on top of cake batter. Spread jam into a somewhat even layer using an offset spatula. Finally, sprinkle generously with the crumb mixture you made first, covering the top of the cake all the way to the edges. Bake for 35 to 38 minutes or until crumb topping is slightly golden brown and jam is bubbly; a toothpick inserted near the center should come out mostly clean.

The secret technique that makes this cake so fabulous is straight from my grandma’s recipe box: mixing the baking soda directly into the sour cream. You’ll notice after doing this that the sour cream gets noticeably foamy—this added air makes for an even softer, lighter cake.

That said, the recipe will still work if you accidentally mix the baking powder AND baking soda in with the flour like most other baked goods (trust me, I’ve done this plenty of times myself). Fret not, your cake will turn out just fine! You probably won’t even notice a difference unless you’re tasting them side by side (I have compared them side by side and I can discern a subtle difference in texture, but it’s certainly not a make-or-break difference).

Flavor Variations:

While you can easily mix up the flavor profiles of this recipe by simply changing out the jams and the extracts, here are a few ideas to make it your own:

Blueberry lemon: Rub 1 teaspoon of lemon zest in with the sugars for both the crumb and cake mixtures; replace almond extract with lemon extract, and use blueberry jam or blackberry jam. Could also experiment with orange or lime zest too!

Fruity coconut: Replace almond extract with coconut extract, and whole milk with coconut milk. Add a few tablespoons of shredded coconut to the crumb topping mixture. This version goes particularly well with tropical jam flavors like guava, mango, or pineapple!

Cinnamon fig: Add 1 teaspoon of cinnamon to the crumb topping mixture, and use your favorite fig jam for a fabulous fall-like flavor.

Ingredient Notes & Substitutions

Sour cream: Use full fat sour cream in this recipe. While you can technically use whole Greek yogurt (just please don’t use low or non-fat), the resulting cake won’t be quite as moist and tender as cake made with sour cream. It really is the secret ingredient in a fabulous cake! Remember, fat adds more than just flavor, it also adds moisture, richness, and contributes to a tender texture.

Jam: You can pretty much use any sweet fruit jam in this recipe, store bought or homemade. You’ll need 6 tablespoons worth (a little over 1/3 cup) so it’s a great way to use up that partial jar you’ve had in your fridge for awhile. You can even mix complementary jams if you have a few random jars that need to be used.

If your jam is on the thick side, microwave it briefly to loosen it up a bit; this will make it easier to spread on top of the unbaked cake batter.

I do not recommend using fresh fruit or fruit puree in this recipe, as it’ll be much too watery. Fruit jam is cooked down and thickened with pectin (either natural or added), so it holds up in the heat of the oven and won’t make the cake underneath soggy.

Almond extract: This is optional, but I love the hint of almond paired with fruits like raspberry and blueberry. Feel free to leave it out (I’d recommend increasing the vanilla to 1 ½ teaspoons if so), or you can swap for lemon, coconut, or other extract of your choice.