Rhubarb Crumb Cake

Rhubarb crumb cake: soft cake covered with lots of tangy rhubarb and topped with sweet streusel. Ready in about 1 hour.

Are you searching for a delicious cake to feed a crowd, cheap, easy, and quick to make? You’ve found it! This rhubarb crumb cake checks all these boxes:

• Taste and texture: amazing! It is sweet and tangy, soft and crunchy, light yet comforting.
• Cheap: pick your rhubarb in the garden, mix a few other super cheap ingredients.
• Easy: all you have to do is a bit of chopping and a bit of stirring.
• Quick: five minutes chopping the tangy stalks, less than five minutes for mixing the crumbles, and another five minutes for stirring the batter. The rest happens in the oven. And altogether, you will only need about one hour.

Do you need more rhubarb dessert ideas? Check the recipes for Rhubarb Crisp with Apples and Oatmeal, Rhubarb Loaf Cake with Blackberries, or Rhubarb Crumble Tart with Strawberries.

What do you need?

Rhubarb:

• One of my favorite seasonal plants. If you want to learn more about dealing with it in the kitchen, make sure to read “What to Do with Rhubarb (Cook, Bake, Preserve).”
• You will need about 750 g/ 1.7 lbs of cleaned stalks. Discard the leaves; they are poisonous.
• Wash and dry the stalks and cut them into pieces, about 1.5-2 cm/ 0.6-1-inch.
• You can make the crumble cake using frozen rhubarb as well. Defrost it in the sieve and pat it as dry as possible with kitchen paper before placing it on the batter.

Crumbs:

• My favorite and easiest streusel/crumbles recipe uses ingredient amounts that are very easy to remember and scale:
• 2 parts flour + 1 part granulated sugar + 1 part unsalted butter
• In this recipe: 300 g flour + 150 g granulated sugar + 150 g unsalted butter
• Of course, this calculation works best when you are using a scale to measure the ingredients. But that is what I always recommend anyway: use a digital kitchen scale; it makes a lot of a difference in baking (Amazon affiliate link).
• You will need 2 ½ cups flour + ¾ cup granulated sugar + ⅔ cup unsalted butter when it comes to cups. Less easy to remember and to scale, unfortunately.
• Additions: a pinch of salt, vanilla extract.

Batter:

• Sugar
• Unsalted butter, soft
• Pinch of salt
• Eggs: at room temperature
• Pure vanilla extract
• Flour: I often use cake flour, but all-purpose is fine as well.
• Baking powder
• Yogurt makes the cake base moist, soft, and comforting; it’s a great addition!

How to make a crumb cake with rhubarb?

• Clean and chop the stalks, set them aside.

Crumb topping:

• Mix sugar, flour, and a pinch of salt in a bowl.
• Cut cold butter into small pieces and add them to the bowl together with a little vanilla (optional). Work in with the handheld mixer (dough attachment) or with your hands. If working with your hands, make sure that they are cold as well. Place topping in the fridge while you make the batter.

Batter:

• Beat soft butter, sugar, and salt until light and fluffy (1).
• Add eggs, one at a time, beating well in between, about 1-2 minutes beating time per egg. Stir in vanilla extract (2).
• Mix flour and baking powder, mix quickly into the butter mixture together with the yogurt (3).

Bake:

• Spread the batter onto a large baking tray lined with baking paper (1).
• Cover with rhubarb (2).
• Top with the crumbs (3).
• Bake for 40-45 minutes until the crumbs are golden brown and slightly crunchy.

Variations:

You can swap the rhubarb for pretty much any other fruit or berries. For example, I love to make similar crumble cakes with peaches or nectarines, plums, cherries, mixed berries, and so on.

Tips for making the crumbs

• For nicely crispy, larger crumbs, use chilled butter as instructed before.
• Alternatively, you can melt the butter in a small pan and mix it with the flour using a fork. In this case, the crumbs will be softer, smaller, crumblier.
• Both versions are delicious, but I prefer the cold butter version; I like the texture of the crumbs better.
• You can slightly decrease the amount of sugar used when making streusel if you would like the rhubarb crumble cake to be less sweet. However, in this case, I prefer to use the whole amount because rhubarb is a very tart plant.
• You can add some cinnamon/nutmeg/cardamom/allspice to the crumble topping.

How to serve?

You can cut it into 12 large pieces or 24 smaller ones. The crumb cake with rhubarb can be served lukewarm or at room temperature. When serving lukewarm, try it with a generous dollop of vanilla ice cream. When serving it at room temperature, a bit of whipped cream would be perfect.

Make ahead and store

• You can make it one day in advance. Let it cool completely on the tray and cover with a kitchen towel once cooled. However, the crumbs will lose their crunch after a while. The cake will still be scrumptious, though, but even softer than regular.
• You can solve that by placing the tray in the preheated oven for another 10 minutes or so. Then, serve lukewarm or let cool again and serve.

Can you freeze a crumb cake?

• Yes. You can freeze the pieces on the tray or a large plate. Once solid, transfer them to freezer bags and freeze them for up to 3 months.
• Defrost in the refrigerator or on the counter. You can also place the frozen pieces on a baking tray again and bake them until heated through and slightly crunchy again, about 10-15 minutes at 180 degrees Celsius/ 350 degrees Fahrenheit, but check.

More crumb cakes:

• German Apple Crumble Cake
• Cherry Crumb Pie
• German Plum Cake - Zwetschgenkuchen Recipe
• Coconut and Cherry Cake
• Red Currant Cake - German Recipe