Banana Poppy Seed Cake with Lemon Buttercream is a unique combination of bananas, poppy seeds, and lemon ~ you can whip up this easy one bowl cake in no time.

Banana Poppy Seed Cake is the perfect snack cake
When you’re ready for a change from the same old banana bread, this cake really hits the spot. You won’t be expecting the crunch of the poppy seeds or the tang from the lemon frosting, but they’re lovely! If you’re going to share it, be sure to have copies of the recipe ready to go, you’re gonna get asked.

This is a classic banana cake with the footprint of a blondie
I don’t know why I haven’t thought to combine all these elements together before, they make for a cake that’s unusual but familiar at the same time.
What you’ll need
- ripe bananas
- butter ~ unsalted and room temperature
- sugar ~ granulated
- sour cream
- egg
- flour ~ all purpose
- poppy seeds
- vanilla extract
- salt and baking soda
- confectioner’s sugar
- lemon juice

How to whip up a one bowl banana cake
No need to haul out the heavy equipment for this banana snack cake ~ just a whisk and a bowl will do fine.
- Cream the butter, sugar, and sour cream together until light and fluffy.
- Beat in the egg, mashed banana, poppy seeds, and vanilla.
- Add the dry ingredients and whisk just until blended.
- Bake!

Lemon buttercream sets this easy banana cake apart from the rest
I’m generous with this particular frosting, which has a similar tangy quality to a cream cheese frosting, but it’s even easier to whip up. You might know it from my Blueberry Zucchini Cake with Lemon Buttercream. It’s butter-heavy, and because of that I think it tastes best chilled, so I keep my cake in the refrigerator until I’m ready to eat.

It’s no secret that I love poppy seeds ~ I use them all the time, in everything from Lemon Poppy Seed Pancakes to Chicken Salad with Poppy Seed Mayonnaise. They just add that special touch to so many foods. I buy them in bulk, which means I always have some on hand to add to my recipes.
Ingredient spotlight: BULK POPPY SEEDS

If your local store doesn’t carry them, you can find poppy seeds in bulk, online, HERE. To store extra poppy seeds, put them in an airtight container in the refrigerator (6 mos) or freeze them, (1 year).

“Absolutely amazing. I now have to gift the rest of it so I won’t eat anymore. I did use zest in the frosting. It was perfect.” ~Leia

Banana Poppy Seed Cake with Lemon Buttercream
Ingredients
- 2 Tbsp unsalted butter, at room temperature
- 2/3 cup sugar
- 1/2 cup sour cream
- 1 large egg, room temperature
- 2-3 ripe bananas, mashed (to make about 3/4 cup mashed)
- 1/3 cup poppy seeds
- 1 tsp vanilla extract
- 1 cup flour
- 1/4 teaspoon salt
- 1/2 teaspoon baking soda
lemon buttercream
- 1/2 cup unsalted butter, at room temperature
- 2 cups confectioner’s sugar
- juice of 1 lemon, about 2 Tbsp
- the tiniest drop of yellow food coloring, optional
Instructions
- Set oven to 350F Lightly spray a 9×9 square baking pan. I like to line it with parchment paper so I can lift the cake out after baking for easy frosting and cutting.
- Cream the butter, sugar, and sour cream together until light and fluffy. Beat in the egg, mashed banana, poppy seeds, and vanilla.
- Whisk the flour, salt, and baking soda together and add to the wet ingredients. Mix until just blended.
- Turn the batter out into the pan and smooth out evenly. Bake for about 35 minutes, or until the top is just turning golden and the middle is set. A toothpick inserted in the center should be free of wet batter.
- Let cool on a rack completely before frosting.
- Make the frosting by beating the butter and sugar together with the lemon juice and food coloring, if using. Add a touch more juice if the frosting is too thick, or a little more sugar if too thin.
- I like to store the cake in the refrigerator, and it will keep for up to a week.
Notes
Notes:
- Add the zest of the lemon to the frosting if you like for even more lemony flavor.
- Substitute chopped walnuts or pecans for the poppy seeds.
- Substitute cream cheese for the butter in the frosting.
Nutrition

What a great combination of flavours! And I love that crunch you get from poppy seeds! Looks delicious, and that frosting on top- just heavenly!
Poppy seeds and lemon? Say no more — love those two flavors together. The bananas are a bonus. 🙂
Wishing I had a piece of this cake right now with my coffee. YUM!
You caught me, I’ve got a cold slice straight from the fridge sitting next to my coffee cup!
This cake looks so moist and rich I want to shove a (LARGE) piece into my mouth. And that frosting looks so creamy and luscious. I’m making this one, Sue.
Omg that frosting looks so luscious! I love how thick you’ve spread it ;D
It’s all about the frosting to cake ratio 😉
Oh this looks so moist and delish!!! Especially that icing. I want to take bite!!!
I also love the suggestion for swapping the poppy seeds for walnuts!! I think that would go down so well with my kids for afternoon tea!
This is a perfect tea cake, thanks Claire.
Loving the lemon buttercream here! And the banana cake looks perfect. Craving 🙂
A little lemon buttercream never hurts 😉
This lovely cake sure would be good with my coffee this morning! What a terrific flavor combination and that buttercream looks dreamy! Sharing and pinning 🙂
Hmmm, would it be legal to have this for breakfast? It looks so good I want it now! And certainly easy enough to make before anyone else is awake! Pinning and sharing!
Of course I was going to mention that I’ve already had it for breakfast…twice. But I thought that might be inappropriate 😉
I do love adding poppy into the banana cake batter. Your version with lemon buttercream looks fabulous, Sue.