Keto Rhubarb Cake Recipe (The One That Won’t Make You Miss Sugar)

If you’re here, you probably love rhubarb or maybe just hate diets that taste like cardboard. Either way, you’re about to get a keto rhubarb cake that’s moist, simple, and doesn’t taste like it’s missing anything, especially not flavor.

This is the cake I make every time rhubarb is in season, or someone’s about to break their diet. Works like a charm. It’s tart, sweet (without sugar), and holds up even if you sneak a slice for breakfast. Ask me how I know.

And yes, this version is low carb, keto-friendly, gluten-free, and free of fake food vibes. You could call it a simple rhubarb cake, or even a rhubarb coffee cake, if you’re into having cake with coffee (which you should be).

Why Rhubarb Works for Keto

Rhubarb has a sharp, almost lemon-like flavor. It’s naturally low in sugar and carbs, making it perfect for keto rhubarb recipes easy to make and stick to. It’s one of those plants your grandma might’ve grown, chopped up, and baked into something that made your whole house smell like childhood.

When you cook it just right, it turns soft, a little jammy, and goes great with anything creamy, like a cheesecake, whipped topping, or buttery cake batter. That’s why people love rhubarb desserts, they hit that sweet-sour spot just right.

Ingredients You’ll Need

For the cake:

• 1 ½ cups almond flour
• ½ cup coconut flour
• 1 cup powdered erythritol (or any keto sweetener)
• 1 tsp baking powder
• ¼ tsp salt
• ½ tsp cinnamon (optional but good)
• ½ cup unsalted butter (softened)
• 4 large eggs
• ½ cup sour cream or full-fat Greek yogurt
• 1 tsp vanilla extract
• 2 cups chopped rhubarb (fresh or frozen, drained well)

For topping (optional but makes it feel like oma’s rhubarb cake):

• ¼ cup chopped pecans or walnuts
• 1 tbsp sweetener
• Pinch of cinnamon

Step-by-Step Instructions to making Keto Rhubarb Cake 

1) Preheat and Prep

Set your oven to 350°F (175°C). Line a 9×9-inch pan with parchment or grease it. I prefer parchment—makes it feel like you know what you’re doing even when you don’t.

2) Mix the Dry

In a big bowl, combine the almond flour, coconut flour, sweetener, baking powder, salt, and cinnamon. Stir it up until everything looks like it belongs together.

3) Add the Wet Stuff

In another bowl, beat the butter until it’s creamy. Add the eggs one at a time. Mix in the sour cream and vanilla.

Now, fold the wet mix into the dry stuff. Don’t overdo it. You’re not making a sponge—you want that moist rhubarb cake feel.

4) Add Rhubarb

Gently stir in your chopped rhubarb. If you froze it, make sure it’s drained. You don’t want soggy cake.

5) Optional Topping

Mix your nuts, sweetener, and cinnamon. Sprinkle on top if you’re aiming for that rustic rhubarb kuchen vibe.

6) Bake It

Pop it in the oven for 35 to 45 minutes. Check around the 35-minute mark. A toothpick should come out mostly clean, maybe with a few crumbs.

Cool for at least 15 minutes. Then slice it. Eat one slice. Pretend it’s your last. Then have another.

Substitutions That Still Work

Want to go a little off-script? You’ve got options:

• Swap sour cream with buttermilk to copy those rhubarb recipes with buttermilk vibes.
• Use a boxed keto cake mix and throw in rhubarb for a rhubarb cake with cake mix recipe marshmallows twist—skip the marshmallows though, they’re not really keto unless you’ve got a special low-carb version.
• Add a layer of cream cheese for a low carb cheesecake feel.
• Use strawberries and rhubarb together if you love strawberry rhubarb recipes or you’re into keto strawberry rhubarb recipes.

A Little Rhubarb Backstory (Because Someone Always Asks)

My grandma called it “pie plant.” She had a garden full of it, and every spring she made rhubarb sheet cake for what felt like the whole town. One of those cakes with a custardy bottom and a crisp top. Totally not keto. But this version? It brings back the same smell and smile, minus the blood sugar spike.

People like oma’s rhubarb cake because it feels like something passed down, even if it’s your first time baking it.

Make It a Showstopper

Want your cake to stop the scroll on Pinterest? Here’s what works:

• Slice it clean, stack it tall.
• Dust with a little powdered sweetener (looks fancy).
• Top with a dollop of whipped cream or a keto icing drizzle.
• Serve it on vintage plates. People go nuts for anything that looks like their aunt’s kitchen.

More Rhubarb Cake Recipes You’ll Probably Try Next

Once you taste this one, chances are you’ll want to branch out. Try these too:

• French rhubarb cake – buttery, more dense, often with yogurt or buttermilk
• Rhubarb coffee cakes – a chunkier crumb, perfect for brunch
• Rhubarb desserts recipes – pies, crumbles, muffins, all begging to be keto-fied
• Rhubarb kuchen recipes – think German simplicity with a cake bottom and fruity top

How to Store It (If There’s Any Left)

This cake keeps in the fridge for 4-5 days. Cover it up or stick it in an airtight container. It also freezes like a champ. Wrap in plastic then foil, or just use a freezer bag.

To thaw, leave in the fridge overnight. Or if you’re impatient (no judgment), microwave for 20 seconds.

Dessert Swaps and Add-Ons

You can totally switch gears and use this base for other desserts keto style:

• Mix in strawberries to turn it into a strawberry cake keto version
• Add a cheesecake swirl for a low carb strawberry cheesecake vibe
• Use blueberries instead of rhubarb if you ran out—no rules

For other sugar free rhubarb recipes low carb lovers, try roasting rhubarb with a bit of sweetener and cinnamon. Serve it warm over keto ice cream or Greek yogurt. Chef’s kiss.

What People Say (That I Actually Believe)

“I didn’t tell my husband it was keto. He ate three slices.”

“I brought this to work. No one knew it was low carb. Now I’m the cake lady.”

“My kids ate it. That’s the real review.”

Conclusion

This easy rhubarb cake is a no-fuss, feel-good dessert. Whether you’re trying to keep it keto or just looking for new rhubarb recipes, this one ticks the boxes. It’s soft, tart, sweet without sugar, and better the next day. You can call it the best rhubarb recipes contender without sounding full of yourself.

Make it once, then do what I did—tweak it till it feels like yours. That’s when a recipe becomes more than just a recipe. It turns into something people remember.

And that, my friend, is the kind of cake worth baking.

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