Brown butter cider filling is sandwiched between two moist apple spice cakes for an orchard-inspired New England riff on the classic whoopie pie.
Preheat the oven to 375°F. Line two baking sheets with parchment.
To make the cakes: In a large mixing bowl, beat together the butter, oil, and sugar until blended. In a separate bowl, whisk together the flour, salt, baking powder, baking soda, and spices. Add half of the dry ingredients to the butter mixture and stir to combine.
In a large measuring cup, whisk together the buttermilk, eggs, boiled cider, and applesauce. Add to the bowl and mix until combined. Add the remaining dry ingredients and beat at medium speed for 30 seconds. Scrape the bowl and beat for 15 seconds more.
Scoop the batter onto the prepared pans, using a tablespoon scoop for small whoopie pies or a muffin scoop for large ones, leaving 1 1/2" between each. Bake the cakes for 12 to 14 minutes, until the tops are set and the edges just beginning to brown.
Remove the cakes from the oven and let them cool right on the pan.
To make the filling: Place the butter in a medium saucepan over medium heat. Cook without stirring until the butter melts and separates; simmer for 8 to 10 minutes. As the water cooks off the butter will become clear, and the solids will sink to the bottom and start to brown. When the butter smells nutty, remove it from the heat and pour it into a mixing bowl (no need to strain).
Add the salt and cinnamon and let cool to lukewarm. Mix in half the confectioners’ sugar. Add the shortening and boiled cider and mix well.
Scrape the bowl, then stir in the remaining sugar. Beat in the milk or cream, 1 tablespoon at a time, until the mixture is stiff but fluffy.
To assemble: Scoop 2 tablespoons filling and sandwich it between the bottoms of two baked cakes. Repeat with the remaining cakes and filling.
Store whoopie pies covered at room temperature for one day, or refrigerate, well wrapped, for up to a week.
Stirring 2 tablespoons Cake Enhancer into the cake batter along with the rest of the dry ingredients gives some added lift to your whoopie pies. Give it a try!
