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Wide image of banana bar sliced with cream cheese icing on a white plate.

Easy Cake Mix Banana Bars with Cream Cheese Frosting

Course: Dessert
Cuisine: American
Keyword: cake mix banana bars with cream cheese frosting
Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes
Servings: 15 slices
Calories: 314kcal
Author: Kara @ Quick and Easy Baking
These cake mix banana bars are moist banana cake on the bottom with a rich cream cheese frosting on the top and are so quick and easy to make.
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US Customary - Metric

Ingredients

For the cake:

  • 3 medium-sized very ripe bananas, mashed
  • 1 (14 ounce) box yellow cake mix
  • 1 1/2 teaspoon cinnamon
  • 3 large eggs, near room temperature
  • 1/4 cup unsalted butter, melted and cooled down a bit
  • 1/4 cup vegetable oil
  • 1/2 cup sour cream, near room temperature
  • 1/2 cup milk, near room temperature
  • 1 teaspoon vanilla extract
  • 1 cup chopped walnuts or pecans (optional)

For the frosting:

  • ½ cup unsalted butter, room temperature (1 stick)
  • 1 (8 ounce package) cream cheese, near room temperature
  • 1 pinch salt
  • 1 teaspoon vanilla extract
  • 3 cups confectioner's sugar
  • 1 teaspoon milk (may use more if needed to reach desired consistency)

Instructions

For the cake:

  • Preheat the oven to 350 degrees F. Spray a 13x9 inch baking dish with nonstick spray and set aside.
  • Make sure the bananas are mashed well, that the butter has cooled down a bit and that the eggs, sour cream and milk are no longer cold. If they are cold, then it could clump the melted butter when mixed, which could cause the ingredients not to mix well and make holes when the batter is baked.
  • In a large mixing bowl, add all of the cake bar ingredients, except for the nuts and mix with an electric mixer on medium until well mixed.
  • Add the nuts, if desired, and mix in by hand.
  • Pour the batter into the prepared baking dish and bake at 350 degrees F for approximately 30-35 minutes. A toothpick inserted into the center of the cake bars should come out with a few moist crumbs on it, or clean, but no raw batter. Be careful not to over-bake as that will make the cake bars dry.
  • Remove the baked cake bars from the oven and set on a cooling rack to cool completely before adding the frosting.

For the frosting:

  • In a large bowl, add the room-temperature butter and mix well with an electric mixer on medium to medium-high speed until smooth.
  • Add the room-temperature cream cheese and mix well on medium-high speed until smooth.
  • Add the salt, vanilla, confectioners sugar and milk and mix on medium-high speed until smooth.
  • Check the consistency. If it’s too thick, add another teaspoon of milk, mix and repeat until the desired consistency is reached.
  • Add to cooled cake bars.
  • See the notes section for best ways to store these, serve them and for more questions.

Notes

How to Store: Since the frosting on these cake bars is made with cream cheese, these bars should be covered and stored in the refrigerator and can last up to 5-6 days.
How to serve: These cake bars can be served/eaten either chilled, at room temperature, or warmed.
For other questions: Make sure to check out the TIPS & FAQs for this recipe in the blog post, which should answer other questions you may have about ingredients, substitutions, other pan sizes etc.
Nutritional values are an estimate.
*This recipe card may contain affiliate links. As an Amazon Associate, I earn from qualifying purchases.

Nutrition

Calories: 314kcal | Carbohydrates: 32g | Protein: 3g | Fat: 21g | Saturated Fat: 8g | Polyunsaturated Fat: 6g | Monounsaturated Fat: 5g | Trans Fat: 0.4g | Cholesterol: 63mg | Sodium: 24mg | Potassium: 158mg | Fiber: 1g | Sugar: 27g | Vitamin A: 411IU | Vitamin C: 2mg | Calcium: 37mg | Iron: 0.5mg