Well, Let Me Tell You About This Protein Cake

Listen, anyone who’s ever caught me elbow-deep in flour at 10pm with a mug of tea in one hand knows: I bake for feelings as much as flavor. This cinnamon swirl protein cake started as a rescue mission for some sad overripe bananas (turns out, protein powder covers a multitude of sins). One wintry afternoon, the house smelling like a bakery, I gave it a go. The result? A cake I’ve made at least two dozen times since, usually when I want something homey but still feel slightly virtuous. Oh! And if you’ve ever plopped protein powder in a recipe and ended up with something… oddly chewy, trust me, I’ve been there. This one? Fluffy. Swirly. Delicious.

So, Why Would You Love This?

I make this when the weekend calls for a pick-me-up (or when I just can’t face another bland protein shake). Actually, my family goes a bit wild for it because it tastes sort of like a cinnamon bun and a classic snack cake did a protein-packed high five. And honestly, it’s nice not having to lie to myself about cake for breakfast. I’ve even grabbed a slice on my way to work (sometimes still half asleep, wearing two different socks — you know the drill). If you’re bored of dry protein bakes, you might finally have met your match here.

What You’ll Need (With Swaps and a Side of Sass)

1 ½ cups oat flour (Sometimes I’ll blitz up old-fashioned oats in a blender — it’s honestly quicker than finding oat flour at my local shop…)
2 large eggs (I’ve subbed in flax eggs when baking for my vegan cousin — works fine, just a tad more dense)
2 very ripe bananas (if yours are slightly green, just microwave for 20 seconds — not perfect, but it’ll do in a pinch)
1 cup Greek yogurt (Plain works best; my grandma swore by vanilla, and I do like the extra sweetness)
1 scoop vanilla protein powder (I’m not brand loyal, though some folks swear by MyProtein or Orgain)
⅓ cup unsweetened applesauce (if I’m out, melted butter or even mashed pumpkin gets swapped in — no shame)
1 ½ tsp baking powder
1/3 cup coconut sugar (or brown, or heck, white… It’s cake, not rocket science)
1 ½ tsp cinnamon (plus extra for swirling on top, because you can’t overdo it here)
Pinch of salt (I usually wing it — a lazy two-fingers pinch does the job)
1 tsp vanilla extract (Or whatever you can find in the cupboard, tbh)

How I (Usually) Throw This Together

Preheat your oven to 350°F (180°C)! I always forget and have to wait. Should probably tattoo this on my hand.
Line a loaf pan with parchment paper, or just grease it well. I have an old nonstick pan that’s seen better days but still gets the job done. Don’t stress if the paper creases — it’s rustic, right?
Mash your bananas in a big bowl. (I sometimes end up with lumps, but they disappear in the bake. Don’t fret.)
Whisk in eggs, Greek yogurt, applesauce, vanilla, and coconut sugar. This is where I sneak a taste — judge if you must.
In a separate bowl, combine oat flour, baking powder, salt, and protein powder. (If you’re using homemade oat flour, pat yourself on the back here.)
Pour the wet mix into the dry — gently, now! Overmixing is the enemy. If it looks a bit gloopy or thicker than you imagined, don’t panic; it’ll work out.
Spread half the batter into the pan, then sprinkle a hearty layer of cinnamon and some coconut sugar over it. Swirl it a little with a knife (not an exact science, more…happy art?)
Top with the rest of the batter and another swirl of cinnamon. If you’re feeling extravagant this morning, a pinch of extra sugar on top makes a lovely crust.
Bake for 35-40 minutes, or until a skewer comes out clean-ish (a crumb or two is fine — wet batter is not). The one time I took it out too soon, well, let’s just say it was less cake, more pudding… Not the good kind.
Cool in the pan for 10 minutes, then lift out (careful, it’s hot!) and let cool a bit longer before slicing. Or don’t, we’ve all burned our tongues on fresh cake.

Notes (Stolen From My Own Mishaps)

If your bananas are more grey than brown, probably just toss them and grab new ones. Trust me.
I used to think more protein powder meant higher nutrition; actually, it sometimes makes the cake dry and weirdly rubbery.
Let it cool completely before wrapping — once, I covered it warm and, well, let’s just call that batch “steam cake.”

How I’ve Switched Things Up (And Goofed Occasionally)

One time I tossed in a handful of chopped pecans — lovely crunch.
Blueberries sounded brilliant, but honestly, they kinda disappeared flavor wise beneath the cinnamon. On second thought, I’d stick to apples if you want something fruity.
Subbed in chocolate protein powder. Tasted good, but very much Not a cinnamon swirl cake anymore. Still, not a disaster.

If You Don’t Have All the Gear

You’ll want a loaf pan, but I’ve actually used a brownie tin in a pinch (just check it early — it bakes faster and can dry if you’re not paying attention). If you’re missing a whisk, a fork and some enthusiasm do fine. Blender for oat flour is optional — old-fashioned elbow grease also works, though it’s an arm workout.

How to Store (If There’s Any Left, Ha!)

It keeps in an airtight container on the counter for about 2 days, though honestly in my house it never lasts more than a day! If you’re super organized, you can freeze slices for grab-and-go breakfasts. Just, uh, don’t expect to find any if you share your house with teens or cake thieves (aka spouses).

Ways We Like to Serve It

I’m not above slathering a warm slice with butter. Sometimes, I’ll stack pieces up with yogurt and maple syrup for a fancy breakfast. My little nephew likes his “with sprinkles, Auntie!” And occasionally, mid-afternoon, I’ll just grab a piece with tea — extra cinnamon on top, just for me.

Lessons Learned (Or, Mistakes Baked In)

I once tried to rush the cooling step and regretted it — seriously, let it cool most of the way before slicing or you’ll have a crumbly catastrophe.
Don’t skip the parchment if your pans are even a little sticky. Sometimes I think I can get away with it, but… no.

Some Real Questions I’ve Gotten (and My Very Honest Answers)

Can I use almond flour instead of oat?
Honestly, I’ve tried — the texture goes pretty dense, but it works if you like a fudgier feel. Maybe add a splash more yogurt.
Is there a way to make this dairy-free?
Yep! Dairy-free yogurt swaps in easily; just watch the sweetness. Vanilla soy yogurt worked well for me, but coconut yogurt was a bit heavy. Your mileage may very.
Do I have to use ripe bananas?
Still tastes good with just-yellow ones, but the riper the better for sweetness. Actually, overripe is my preference — those mooshy ones everyone turns up their nose at.
Can I double it for a crowd?
Absolutely; just use a bigger pan or two tins. Keep an eye on baking time — sometimes mine’s been done 10 minutes early when spread out.
Is it kid-friendly?
Sure thing! I mean, my nephew calls it “breakfast cake,” so yeah. Just maybe skip the protein powder for tiny ones if you’re worried.

Random, but I once whipped this up mid-move (kitchen boxes everywhere, no electric mixer, no patience). Still came out, somehow. Cake resilience is underrated, isn’t it?

If you’re after a bit more protein bake inspiration, I really like the banana protein recipes over at Running on Real Food. For the sciencey types, Sally’s Baking Addiction breaks down ingredient swaps pretty clearly too. Just in case you want to rabbit hole — no judgment!

Cinnamon Swirl Protein Cake