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Banana Poppy Seed Cake with Lemon Buttercream

Banana Poppy Seed Cake with Lemon Buttercream

A moist two-layer banana cake flecked with poppy seeds and finished with fluffy lemon American buttercream. The recipe yields approximately 10–12 servings.
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Prep Time 30 minutes
Cook Time 25 minutes
Total Time 2 minutes
Servings: 10 servings
Ingredients Method Notes

Ingredients
  

Banana Poppy Seed Cake
  • 1 3/4 cups (220 g) All-purpose flour
  • 1 teaspoon Baking soda
  • 1/2 teaspoon Baking powder
  • 1/2 teaspoon Fine salt
  • 1 tablespoon Poppy seeds
  • 1/2 cup (113 g) Unsalted butter, softened
  • 3/4 cup (150 g) Granulated sugar
  • 2 eggs Large eggs, room temperature
  • 1 teaspoon Vanilla extract
  • 1 1/4 cups, about 3 medium bananas Mashed very ripe banana
  • 1/2 cup (120 ml) Buttermilk
  • 1 lemon, optional Finely grated lemon zest
Lemon Buttercream
  • 1 cup (226 g) Unsalted butter, softened
  • 3 1/2-4 cups (400-460 g) Confectioners' sugar, sifted
  • 2-3 tablespoons Freshly squeezed lemon juice
  • 1 tablespoon Finely grated lemon zest
  • 1-2 tablespoons, as needed Heavy cream or milk
  • 1/4 teaspoon Salt

Method
 

Step-by-Step
  1. Heat the oven to 350°F (175°C). Grease two 8-inch round cake pans and line the bottoms with parchment paper.
  2. Whisk the flour, baking soda, baking powder, fine salt, and poppy seeds together in a medium bowl.
  3. Beat the softened butter and granulated sugar for 3–4 minutes, until light and fluffy. Add the eggs one at a time, beating after each addition, then mix in the vanilla and optional lemon zest.
  4. Mix in the mashed bananas. Add the dry ingredients in two or three additions, alternating with the buttermilk, and mix only until the batter is combined.
  5. Divide the batter evenly between the prepared pans. Bake for 25–30 minutes, until the centers spring back lightly and a toothpick inserted in the middle comes out with a few moist crumbs.
  6. Cool the cakes in their pans for 10 minutes, then turn them out onto wire racks and cool completely.
  7. For the buttercream, beat the softened butter until smooth. Gradually add the sifted confectioners' sugar, then beat in the lemon juice, lemon zest, and salt.
  8. Add the heavy cream or milk a little at a time until the frosting is spreadable. Beat for another 2–3 minutes, until fluffy.
  9. Place one cake layer on a serving plate and spread it with buttercream. Add the second layer, then frost the top and sides.

Notes

Use heavily speckled, fully ripe bananas for the best sweetness, moisture, and flavor. Cool the cake completely before frosting; refrigerate the cooled layers for 20–30 minutes if you want especially clean assembly. Store covered in the refrigerator and bring to room temperature before serving.