Banana Cake with Butter Rum Frosting

If you love the banana flavor, try this banana cake with butter rum frosting.  It is a family favorite for Sunday night dinner or just when celebrating having a few over-ripe bananas.  You will love the frosting which packs robust flavor and sweetness.

Ingredients for Banana Cake

For this recipe, you will need cake flour, baking powder, baking soda, sugar, salt, butter, eggs, 2-3 ripe bananas (equalling 1 cup when mashed), buttermilk, and vanilla.  See notes below regarding banana ripeness and cake flour versus all purpose flour.

How Ripe Should my Bananas Be?

The best bananas to use are slightly soft.  Too brown/ black is too mushy and green, firm bananas are also not suitable.  In this photo, the dark banana would be too mushy to use.  The middle banana would be perfect, as some brown spots are fine.  When you are not sure visually, check for the slightly soft level of firmness.

Cake Flour versus All-Purpose Flour

According to King Arthur Baking Company, the difference in cake flour and all purpose flour is the content of gluten proteins. Cake flour has less protein, resulting in a finer and smoother texture of cake.  So if you have it, use cake flour for cakes when you can.  However, if you do not want to head out to the store just for that, this cake and others can bake just fine with use of regular all-purpose flour.

Ingredients for Butter Rum Frosting

This glaze is a sweet and light.  For this delicious butter rum glaze recipe, you will need butter, 2 tsp rum, two cups of powdered sugar, and 2-2 1/2 T of buttermilk.  You can substitute the buttermilk with regular milk or half and half; however, we recommend the buttermilk.  Also, walnuts are an optional topping.

How to Make the Banana Cake and Butter Rum Frosting

If you are really prepared, you can pull eggs and butter out of the refrigerator about an hour or two ahead of time.  It is ideal to have the eggs at room temperature and butter slightly softened.  If you do not pull them out ahead, don’t worry!  You can chop butter into chunks and soften it in the microwave.  Then, put the two eggs in a bowl of room temperature water for a few minutes while you are getting the rest of the ingredients and supplies ready.

Banana Cake

First, preheat the oven to 350°.  Then grease a 9X13 glass cake pan with cooking spray or butter.  You will use 3 mixing bowls to combine the 3 separate parts of this recipe.

In a medium bowl, you can sift 2 1/4 cups flour with the following other dry ingredients, baking powder, baking soda, and salt. We like to use a wire whisk to combine these ingredients.  Or, you can also use a fine mesh sieve to sift these together.

In a large mixing bowl, cream the softened butter and sugar together with a spatula or wooden spoon.  It is also ok to use an electric mixer on low, if you prefer.  Now, add the eggs into the sugar and butter.

In a small bowl, mash bananas to equal 1 cup.  The amount of bananas truly depends on the size of the fruit.  It seems it often equals about 2-3 medium sized ripe bananas.  Add vanilla and buttermilk to the mashed bananas and mix well.

Now, alternate adding 1/3 each of the dry ingredients and the banana mixture to the sugar butter mixture.  Be sure to mix well after each addition.

Once all of the ingredients are combined, pour into the greased baking dish.  The batter will be thick.

Now bake at 350° for 30 minutes, until the top is golden brown and a toothpick comes out clean.

Butter Rum Frosting

Allow the cake to cool for about 45 min to an hour on a wire rack.  Next, sift the powdered sugar through a fine mesh sieve to strain out any clumps and set aside in a medium mixing bowl.

Then, heat 4 Tablespoons of butter over medium heat in a medium sauce pan.  Melt and heat the butter until it just starts to brown (about 3-5 minutes). Next, add the sifted powdered sugar to the pan of butter and stir with a whisk.  Add 2 tsp of rum as you stir and then the buttermilk.  Continue to stir until it reaches a smooth consistency.  While it is still warm, you will want to pour it onto the cake and begin spreading it quickly.  It will harden as you spread it on.  A little goes a long way, so you will be able to see the cake through the glaze in some places, and that is just fine!  If you happen to need more time to spread it more evenly, heat up your spreading knife under some hot water, dry it off, and then you can use that warm knife to continue spread the glaze after it has hardened.

Optional:  Top with chopped or halved walnuts.

Modifications and Suggestions

• As mentioned throughout this recipe, you can substitute cake flour with all purpose flour if you do not have cake flour or are dreading a trip to the store for just one item!
• This recipe is easily divided in half if you would prefer to have a smaller cake or you don’t have enough ripe bananas, in an 8X8.
• If you have left over buttermilk, be sure to use it up making these homemade buttermilk pancakes!
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  Banana Cake with Butter Rum Frosting

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  • Author: Gnarly Roots
  • Total Time: 1 hour 10 minutes
  • Yield: 12-15 1x

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  Ingredients

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  For Banana Cake

  • 2 1/4 cups cake flour*
  • 1/2 tsp baking powder
  • 3/4 tsp baking soda
  • 1/2 tsp salt
  • 1 1/2 cups sugar
  •  1/2 cup butter (softened)
  •  2 eggs
  • 2–3 ripe bananas (equalling 1 cup when mashed),
  • 1/4 cup buttermilk
  • 1 tsp vanilla
  • *Can substitute cake flour with all purpose flour

  For the Butter Rum Frosting

  • 2 T butter
  • 2 tsp rum (or rum flavor)
  • 2 cups of powdered sugar
  • 2–2 1/2 T of buttermilk*
  • *Can substitute regular milk for buttermilk

   

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  Instructions

  1. If you are really prepared, you can pull eggs and butter out of the refrigerator about an hour or two ahead of time.  It is ideal to have the eggs at room temperature and butter slightly softened.  If you do not pull them out ahead, don’t worry!  You can chop butter into chunks and soften it in the microwave.  Then, put the two eggs in a bowl of room temperature water for a few minutes while you are getting the rest of the ingredients and supplies ready.

  Banana Cake

  1. First, preheat the oven to 350°.  Then grease a 9X13 glass cake pan with cooking spray or butter.  You will use 3 mixing bowls to combine the 3 separate parts of this recipe.
  2. In a medium bowl, you can sift 2 1/4 cups flour with the following other dry ingredients, baking powder, baking soda, and salt. We like to use a wire whisk to combine these ingredients.  Or, you can also use a fine mesh sieve to sift these together.
  3. In a large mixing bowl, cream the softened butter and sugar together with a spatula or wooden spoon.  It is also ok to use an electric mixer on low, if you prefer.
  4. Now, add the eggs into the sugar and butter/sugar mixture.
  5. In a small bowl, mash bananas to equal 1 cup.  The amount of bananas truly depends on the size of the fruit.  It seems it often equals about 2-3 medium sized ripe bananas.
  6. Add vanilla and buttermilk to the mashed bananas and mix well.
  7. Now, alternate adding 1/3 each of the dry ingredients and the banana mixture to the sugar butter mixture.  Be sure to mix well after each addition.
  8. Once all of the ingredients are combined, pour into the greased baking dish.  The batter will be thick.
  9. Now bake at 350° for 30 minutes, until the top is golden brown and a toothpick comes out clean.

  Butter Rum Frosting

  1. Allow the cake to cool for about 45 min to an hour on a wire rack.
  2. Next, sift the powdered sugar through a fine mesh sieve to strain out any clumps and set aside in a medium mixing bowl.
  3. Heat 4 Tablespoons of butter over medium heat in a medium sauce pan.  Melt and heat the butter until it just starts to brown (about 3-5 minutes).
  4. Add the sifted powdered sugar to the pan of butter and stir with a whisk.
  5. Add 2 tsp of rum as you stir and then the buttermilk.  Continue to stir until it reaches a smooth consistency.
  6. While it is still warm, you will want to pour it onto the cake and begin spreading it quickly.  It will harden as you spread it on.  A little goes a long way, so you will be able to see the cake through the glaze in some places, and that is just fine!
  7. If you happen to need more time to spread it more evenly, heat up your spreading knife under some hot water, dry it off, and then you can use that warm knife to continue spread the glaze after it has hardened.

  Optional:  Top with chopped or halved walnuts.

  • Prep Time: 30 min
  • Cook Time: 40 min