Banana Oat Whoopie Pies

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In the “before times”, I had a recipe on the site for Banana Oatmeal Sandwich Cookies. The recipe was adapted from a banana whoopie pie recipe, but in the process became something very different. So different, in fact, that I no longer used “Whoopie Pie” in the recipe title. I had not intended to stray so far from a whoopie pie, but, to be perfectly honest, I just didn’t have the experience at the time to be successful in my adaptation. As with a number of my other re-posted recipes, I took this as an opportunity for a redo – in this case giving the recipe a major makeover. And this time, I would say that I was most definitely successful!

A stack of Banana Oat Woopie Pies

The recipe I originally adapted from (Baking Bites – Banana Whoopie Pies), described the cookies as banana bread-like. There is absolutely nothing wrong with banana bread, but, in my remake, I knew I definitely wanted cake, not bread, to come to mind. That meant finding a different starting point entirely.

There is a recipe in the Bon Appétit Desserts cookbook for a Hot Fudge Banana Pound cake. It was the first recipe I made from that cookbook and it is one I go back and remake fairly often. It proved to be the perfect inspiration for this re-make recipe.

  • I made some adjustments to thicken the batter (increased the flour, reduced the bananas slightly, reduced the eggs by half) so I would get cookies that held their shapes rather than all running together on the baking sheet.
  • I replaced about 1/3 of the all purpose four with oat flour to add a bit of nuttiness and some caramel notes (in my previous recipe, I used quick oats, but they added too much texture and interfered with the rise of the cookies).
  • To build on the caramel notes, I swapped the granulated sugar for toasted sugar and add toffee pieces both to the batter and as a crunchy element in the filling.
  • For the filling, I wanted to make a nod to the classic whoopie pie marshmallow filling but offset the sweetness with a little bit of tangy cream cheese. It is fluffy and creamy with enough structure to avoid squeezing out the sides when you bite into the cookie.
  • Of course, I kept the hot fudge from the Bon Appétit recipe, using it to coat the backs of the cookies rather than swirling through the batter. In my first iteration, there was a ganache used for the same purpose, but it was listed as optional in the recipe – I do not think the hot fudge is optional, the bittersweet notes from the hot fudge are really necessary to add balance to these very sweet cookies.

An image of the Banana Oat Woopie Pies to illustrate the end result of the recipe

Banana Oat Whoopie Pies

This recipe is adapted from Bon Appétit Desserts Hot Fudge Banana Pound Cake
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Course: Dessert
Cuisine: American
Keyword: banana, cookie, cream cheese, fudge, hot fudge, marshmallow, oat flour, oats, sandwich
Prep Time: 40 minutes
Cook Time: 10 minutes
Assembly Time: 30 minutes
Total Time: 1 hour 20 minutes
Servings: 22 cookie


  • bowls
  • Food processor/Blender
  • Electric mixer
  • baking sheets
  • whisk
  • spatula
  • cookie scoop
  • measuring cups
  • measuring spoons


For the cookies

  • 2 cup flour all-purpose
  • 1 cup oat flour
  • 1 teaspoon baking powder
  • 1 teaspoon salt
  • 1/2 teaspoon baking soda
  • 2/3 cup bananas (2 small to medium bananas)
  • 1 teaspoon lemon juice
  • 1 teaspoon vanilla extract
  • 3/4 cup unsalted butter room temperature
  • 1 1/4 cup toasted sugar
  • 2 egg large
  • 1/3 cup toffee pieces

For the filling

  • 1 cup unsalted butter cool room temperature
  • 2 ounce cream cheese cool room temperature
  • 1 tablespoon meringue powder
  • 1 tablespoon heavy cream cold
  • 2 teaspoon vanilla extract
  • 1/2 teaspoon salt
  • 5 ounce marshmallow cream
  • 3 cup powdered sugar
  • 1 1/2 cup hot fudge
  • toffee pieces to taste, for sprinkling on the filling


  • To make the cookies: pre-heat oven to 375°F. Line 2 large baking sheets with parchment paper or a silicone mat.
  • In a medium bowl whisk together the flour, oat flour, baking powder, baking soda and salt. Set aside.
    2 cup flour, 1 cup oat flour, 1 teaspoon baking powder, 1 teaspoon salt, 1/2 teaspoon baking soda
  • Using a small food processor or stick blender, puree the bananas with the lemon juice and vanilla extract.
    2/3 cup bananas, 1 teaspoon lemon juice, 1 teaspoon vanilla extract
  • In the bowl of a stand mixer fitted with the paddle attachment cream together the butter and sugars until light and fluffy.
    3/4 cup unsalted butter, 1 1/4 cup toasted sugar
  • Add the eggs, one at a time, beating well after each one until combined.
    2 egg
  • Either using a silicone spatula to stir by hand or with the mixer on its lowest setting, alternate adding the dry ingredient mixture and the banana mixture. Start and end with the dry ingredients.
  • Fold in the toffee pieces. The batter will be thick and creamy, closer to a very thick cake batter than cookie dough.
    1/3 cup toffee pieces
  • Use a 1 1/2 tablespoon cookie scoop to drop uniformly sized portions of batter on the prepared baking sheet at least 2 inches apart. Bake for about 9-10 minutes; the cookies should be only lightly browned and springy to the touch.
  • Transfer to a wire rack to cool completely.

To make the filling:

  • In the bowl of a stand mixer, beat together the butter, cream cheese, meringue powder, heavy cream, salt and vanilla until creamy and smooth
    1 cup unsalted butter, 2 ounce cream cheese, 1 tablespoon meringue powder, 1 tablespoon heavy cream, 2 teaspoon vanilla extract, 1/2 teaspoon salt
  • Beat in the marshmallow cream until well combined.
    5 ounce marshmallow cream
  • Gradually beat in the powdered sugar, about 1 cup at a time until is is fully incorporated. The mixture should resemble a thick, dense whipped cream and hold stiff peaks. If it is too soupy, place the entire mixing bowl in the fridge for about 20 minutes and then whip again; repeat if necessary.
    3 cup powdered sugar

To assemble the cookies:

  • Spread a layer of hot fudge on the backs of all the cookies, about 1 1/2 to 2 teaspoons per cookie.
    1 1/2 cup hot fudge
  • Pipe a generous amount of the filling on the backs of half the cookies. Sprinkle the filling with toffee pieces.
    toffee pieces
  • Place a second cookie on top of the filling and toffee pieces, pressing down gently until the filling nearly reaches the edges of the cookies.
  • Store cookies in an air tight container.

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