Back in the day, before whoopies were available all throughout the United States, the Amish called these little treats "creamy turtles." They also called them hucklebucks, but there's just something about that name, creamy turtles, that's just so . . . so . . . ghastly. Anyway, legend has it that Amish wives placed creamy turtles in their husband's lunch pails. And when they opened them, the bearded gentlemen would yell, "Creamy turtles!" Just kidding. They'd yell, "Whoopie!" of course.
Make the cakesPreheat the oven to 375°F. Line two half sheet pans with parchment paper.
Put the chopped chocolate in a heatproof bowl. Pour the hot coffee over the chocolate and let sit undisturbed for 2 minutes to allow the chocolate to melt. Whisk to combine.
In a bowl, whisk together the flour, cocoa powder, espresso powder, salt, baking soda, and baking powder for 30 seconds to evenly distribute the leavening.
In the bowl of a stand mixer fitted with the whisk attachment, whisk together the brown sugar and oil until combined. Add the egg and mix.
Add the buttermilk and vanilla to the coffee mixture and mix to combine.
With the mixer running on medium speed, add half of the flour mixture and then add half of the buttermilk mixture to the sugar mixture, mixing after each addition until combined. Add the remaining flour and then the remaining buttermilk mixture, mixing until smooth. Using a large (3-ounce/90-ml) cookie scoop, scoop out the batter and place mounds about 3 inches apart on the prepared sheet pans. Bake until the cakes spring back when gently poked, about 15 minutes. Let cool completely.
Make the fillingIn a stand mixer fitted with the paddle attachment, combine the cream cheese, butter, confectioners sugar, and salt, mixing until smooth.
Scoop 1/4 cup of the filling onto the flat side of a cooled cake and top with another cake, flat side down; press together gently. Repeat until all the cakes are used.
For the cake:
- Increase the baking soda to 1 teaspoon.
- Omit the egg. Replace the buttermilk with 1 cup plain almond milk and 1 tablespoon distilled white vinegar, stirred together and allowed to sit for 2 minutes undisturbed to curdle.
For the filling:
- 1 (8-ounce) package vegan cream cheese and replace the butter with 4 tablespoons Earth Balance Vegan Buttery Sticks.
- Decrease the confectioners sugar to 2 cups. As this mixture is not as stiff as the non-vegan cream cheese filling, sandwich only a few tablespoons in between the cakes.
Gluten-free versionFor the cake:
- Omit the coffee.
- Melt the chocolate by itself in a heatproof bowl set over a saucepan of simmering water (to make a double boiler), stirring constantly until melted.
- Replace the flour with 1 cup finely milled brown rice flour, 1/3 cup sweet white sorghum flour, 3 tablespoons tapioca starch, and 1 teaspoon xanthan gum.
- Replace the oil with 9 tablespoons unsalted butter, softened.
- Cream together the sugar and butter until light and fluffy.
- Increase the eggs to 2 and add one at a time.
- Reduce the buttermilk to 1/2 cup.
For the cake:
- Increase the coffee by 1 tablespoon to make 1/4 cup plus 1 tablespoon coffee total.
- Replace the flour with ½ cup Sprouted Super Flour and 1 cup whole-wheat pastry flour.
- Replace the sugar with 1 cup organic granulated palm sugar.
- Replace the oil with 1/4 cup organic grapeseed oil and 1/4 cup pureed black beans (from a can of cooked organic black beans, pureed in a blender or food processor); first mix together the palm sugar and the oil, then add the pureed black beans, then the egg.