Banana Sheet Cake with Cream Cheese Frosting

Ingredients

• 375 g all purpose flour (3 cups, measured by spoon and level method)
• 1 tsp baking soda
• 400 g mashed overripe bananas (3-4 bananas)
• 150 g vegetable oil (about ¾ cup, see recipe notes below if you want to add some butter for more flavor )
• ½ tsp sea salt
• 150 g brown sugar (¾ cup)
• 100 g granulated sugar (½ cup)
• 3 large eggs
• 2 tsp vanilla extract
• 1 tbsp white vinegar
• 180 mL buttermilk or sour cream
• 1 tsp ground cinnamon
• ¼ tsp ground cloves (optional)
• ¼ tsp nutmeg (optional)
• 170 g unsalted butter (about 1½ sticks, at room temperature)
• 250 g cream cheese block (about 1 package Philadelphia brick cream cheese, at room temperature)
• ¼ tsp sea salt (I like to add ½ tsp for a little salty flavor)
• 2 tsp vanilla extract
• 1½ tbsp dry milk powder (Or use 2 tbsp instant vanilla pudding powder)
• 1 tsp Instant clear jel ((leave this out if you're using instant vanilla pudding powder above))
• 300 g sifted confectioner's sugar

Steps

1. 1

   Preheat the oven to 300°F / 150°C (conventional oven). Butter and line a 9 x 13 inch cake pan with parchment paper. Make sure any exposed sides are lightly brushed with butter to prevent the cake from sticking to it. Set aside.

2. 2

   Place the flour, spices, and baking soda in a bowl and whisk to combine with no lumps. Sift the dry ingredients if any lumps need to be broken up.

3. 3

   Place the bananas in a bowl and mash them up. Some lumps are OK here. You can use a fork or a mixer to do this. Set aside.

4. 4

   In a large bowl, add the oil, salt, white sugar, and brown sugar, and mix until well incorporated. Break any sugar lumps if present. Scrape down the sides if needed. You can also substitute 50 g / ¼ cup of oil with 56 g / ¼ cup melted butter as well for more flavor, if you prefer.

5. 5

   Add the eggs, vanilla, and vinegar, and whisk well to combine.

6. 6

   Place the buttermilk or sour cream in the mixture and whisk to combine well. This mixture should be smooth with no lumps.

7. 7

   Add the flour mixture to the wet ingredients and carefully fold it in. If needed, add the flour mixture in two additions.

8. 8

   While there are still unmixed flour in the batter, add the banana and fold it in gently. Be careful not to overmix the batter after adding the flour to prevent the cake from becoming rubbery.

9. 9

   Pour the cake batter into the prepared cake pan and evenly spread the batter. Lightly shake or knock the cake pan on the counter to remove large air bubbles and to evenly distribute the cake batter.

10. 10

    Bake in the preheated oven for about 50 - 60 minutes, rotating the pan once half way through baking time if needed. The bake time is based on baking the cake in a metal cake pan. Glass pan bake times will vary.

11. 11

    The cake is done when a toothpick inserted into the middle of the cake comes out with just a few cake crumbs stuck to it.

12. 12

    Remove the cake pan from the oven and let the cake cool slightly.

13. 13

    Turn the cake out onto a wire rack and let it cool completely with a tea towel over the cake to prevent it from drying out.

14. 14

    When the cake has cooled down, you can trim the edges for neater sides - but this is optional. You can also transfer the cake back into the cake pan, if you'd like to serve the cake IN the cake pan.

15. 15

    Place the room temperature butter and salt in a mixer bowl with a whisk attachment.

16. 16

    Whisk the butter until the butter is pale, light, and fluffy. This can take up to 10 - 15 minutes, depending on how firm the butter was at the start. Remember to scrape down the sides of the bowl to ensure the butter is whipped evenly.

17. 17

    While the butter is being whipped, place the milk powder and instant clear jel in a bowl, and mix well to disperse the clear jel in the milk powder. You can also use instant vanilla pudding instead here as well.

18. 18

    Once the butter is whipped, add the milk powder mixture, and whisk on high speed to disperse the milk powder well. Scrape down the bowl at least once during this process.

19. 19

    Add the confectioners sugar and whisk it into the butter mixture on low speed until all the sugar has been added.

20. 20

    Once all the sugar is added and mixed in, add the vanilla. Increase the speed to medium high to mix the confectioner's sugar with the butter to make a thick frosting. Scrape down the bowl 1 - 2 times in between to ensure everything is mixing uniformly.

21. 21

    When the butter and sugar have whipped well and you have a fluffy, thick buttercream, scrape the buttercream into a separate bowl and set it aside.

22. 22

    Into the same mixing bowl that you used above, add the cream cheese.

23. 23

    With a paddle attachment, cream the cream cheese. Only use medium speed to make sure the cream cheese is light, creamy, and without any lumps. Scrape the sides and bottom of the bowl to ensure all the cream cheese is being mixed. The unmixed cream cheese will create lumps in the frosting. Avoid over-creaming the cream cheese, as this can make the frosting more liquidy. Cooler cream cheese will retain its thickness better than warm cream cheese.

24. 24

    When the cream cheese mixture is smooth, creamy, thick, and lump free - add the buttercream mixture back into the mixing bowl.

25. 25

    With the paddle attachment still attached, whip the frosting on medium speed (or medium high speed for shorter bursts), to mix the cream cheese and buttercream together. Scrape down the sides to ensure both mixtures are mixing together well.

26. 26

    When the buttercream and cream cheese parts have mixed well together and uniformly, the frosting is ready to be used.

27. 27

    If you want clean, straight edges, you can trim off the edges of the cake. If the cake is domed on top, use a bread knife to slice off the dome to make the top flat.

28. 28

    Alternatively, you can leave the cake as is and serve it on a cake tray, or in the cake pan as well.

29. 29

    Spread the cream cheese frosting evenly on top.

30. 30

    Keep the frosting layer smooth, OR create swirls or other patterns on top. I like to keep the frosting layer plain, but you can also add chopped nuts, crushed cookies, sliced bananas, or even a drizzle of chocolate fudge sauce or salted caramel sauce.

31. 31

    The cake can be refrigerated for about 2 days, but for best results, serve the cake at room temperature. Enjoy!