Mom’s Easy Rhubarb Crumb Bars with a Buttery Crust

Rhubarb crumb bars or Old fashioned rhubarb bars, are sweet and tart with a light crumble topping. The inside is slightly custardy and all that goodness sits on a shortbread type base. They will change anyone’s mind who think they hate rhubarb… I’ve seen it happen.

Also, they’re easy to make and freeze beautifully so you can make a whole batch, no problem!

RHUBARB CRUMB BARS

I grew up having these bars as an afternoon snack and when I got older, as a breakfast with my coffee 🙂 This recipe is an oldie, but it’s a goodie!

I love the versatility of rhubarb. It goes into so many desserts like my Rhubarb and Pear Crumble and my Strawberry Rhubarb Hand Pies. You can even make a Strawberry Rhubarb Lemonade with this recipe from Bless This Mess! But I have to say, my Mom’s recipe using rhubarb is probably my most favorite.

It’s sweet and tart, buttery, and has a custardy type center. Plus, the base tastes similar to shortbread which is amazing if you’re into those flavors.

There are a lot of ways out there to use your rhubarb. And honestly, this sour vegetable (yes, believe it or not!) has a lot to offer. You can read my article about everything you need to know about growing rhubarb plants and dig into our rhubarb craze. It’s a great ingredient and this recipe can really be a perfect dessert to serve during the rhubarb season.

✨Ingredient Highlights

• ✅ Rhubarb: Fresh or frozen rhubarb will work. If using frozen, thaw it completely and drain away the excess liquid before measuring. I find that red and green varieties taste the same, so use whichever you have.
• ✅ All-purpose flour: Flour forms the base and crumb topping and also helps thicken the rhubarb filling. A cup-for-cup gluten-free baking flour should work, although the texture may differ slightly.
• ✅ Butter: Butter gives the bars their rich flavor and crumbly texture. You’ll need softened butter for the base and melted butter for the filling. I use salted most of the time because of the convenience. Margarine can be substituted if necessary with no problems.
• ✅ Granulated sugar: Sugar goes in both the base and the rhubarb filling. Rhubarb is naturally very tart, so the sugar balances its sharp flavor. Avoid liquid sweeteners such as honey or maple syrup because they could prevent the filling from setting properly.
• ✅ Eggs: Eggs bind the crumbly base and give the filling its soft, custardy texture. Large eggs work best, and I like to leave them out at room temperature for about a half hour before starting the recipe.
• ✅ Baking powder and salt: Baking powder keeps the base tender, while salt balances the sweetness and brings out the buttery flavor.
• ✅ Milk: Whole milk gives the filling the richest flavor, but 2% milk, light cream or an unsweetened, neutral-flavored plant milk can also be used.

Directions To Make Rhubarb Bars

Here’s how to make this dessert:

1. Make the crumb mixture: Combine the base ingredients until the mixture looks crumbly but holds together when squeezed in your hand. Press about two-thirds of it evenly into the prepared baking dish, then set the rest aside for the topping.
2. Mix the filling: Whisk together the filling ingredients until smooth. It should have a thin, pourable consistency similar to pancake batter.
3. Assemble the bars: Scatter the chopped rhubarb evenly over the base. Slowly pour the filling over the rhubarb, doing your best to distribute it throughout the pan. Crumble the reserved base mixture evenly over the top.
4. Bake: Bake until the filling has set and a toothpick inserted near the centre comes out clean. Let the bars cool before slicing so the filling has time to finish setting.

Please refer to the printable recipe card below for exact amounts, detailed instructions, and helpful tips to make this recipe perfect every time.

✨Joanne’s Tips

• The crumb mixture might look a little dry, but it should hold together when you squeeze some in your hand. (Like I showed in the photo above). Press the base down firmly enough to hold together, but don’t pack it down excessively.
• If the filling seems too thick to pour, add a small splash of milk at a time until it resembles thin pancake batter.
• Let the melted butter cool slightly before adding the eggs so the heat doesn’t begin cooking them.
• These bars slice much more neatly once they’ve cooled completely. I know waiting is the worst part, but it’s worth it!

Storing and Freezing

Storing these rhubarb crumb bars is easy as pie. (See what I did there?)

This dessert can last in the fridge for about 5- days. Just make sure to use an airtight container or cover really well with plastic wrap, so that the crumb cake doesn’t dry out or take on any fridge odors.

When freezing, make sure to put it in the freezer after it was baked because if you try to freeze it raw/unbaked, the custard/batter layer will not hold up through the thawing process.

If you want to make or freeze ahead, you can freeze the base layer in a baking pan. You can also freeze the rhubarb ahead of time, but the batter layer will have to be made fresh. After the bars are baked, they will last in the freezer wrapped tightly for at least 3 months.

Serving (the BEST part!)

You can serve these rhubarb crumb cake bars slightly warm, or cold, plain with no other garnish. Or, you can dollop a scoop of ice cream or whipped cream beside the bars for an even better dessert experience. Perfect for an afternoon snack or any occasion.

These crumb bars barely lasted a few days when my mom would make them. Just like the Strawberry Rhubarb Bars she’d make, they were breakfast, dessert and after school snacks for my brother and I, so she knew that these ingredients would never be wasted.