Vanilla Bean Whoopie Pies with Nutella Buttercream Filling

My sister has been dying for me to make these forever, so I finally did when I had to bake for a work conference. They were great!

Taste: The cookie/cake part could have used more vanilla, even though I added a vanilla bean and vanilla extract. And the filling could have tasted a little bit more like nutella. But it was a nice, light dessert.

Texture: The cookie/cakes were a little dry (probably because I under-baked the first batch then over-corrected.

Would I make this again?: I would probably make another flavor whoopie pies. Like these pumpkin ones which were AMAZING. 

Vanilla Bean Whoopie Pies
Found: Tracey's Culinary Adventures

2 1/4 cups all-purpose flour
1 1/2 teaspoons baking powder
1/2 teaspoon salt
4 tablespoons unsalted butter, at room temperature
4 tablespoons vegetable shortening
1/2 cup granulated sugar
1/2 cup packed light brown sugar
2 large eggs, at room temperature
1/2 cup buttermilk, at room temperature
2 tablespoons milk, at room temperature
1 teaspoon baking soda
1 teaspoon white vinegar
seeds from 1 vanilla bean (or 1 teaspoon vanilla extract)

Preheat oven to 375 F. Line two baking sheets with parchment paper.

In a medium bowl, whisk the flour, baking powder and salt together. In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, shortening and both sugars on medium speed until light and fluffy, about 3-4 minutes. Add the eggs and buttermilk and beat until combined (your batter may look curdled - mine definitely did, but it came together when I added the flour).

Combine the milk, baking soda, and vinegar in a small measuring cup. With the mixer on low add half of the flour mixture, followed by the milk mixture and then the rest of the flour mixture. Beat just until everything is combined. Add the seeds from the vanilla bean and beat for another minute, until everything is completely combined.

Using a small cookie scoop, drop the dough onto the prepared baking sheets, leaving about 2 inches of space between cookies. Bake the cookies, one sheet at a time, for 8-10 minutes, or until they are set and just beginning to brown. Let the cookies cool on the baking sheets for a few minutes before transferring to a wire rack to cool completely.

Prepare the filling with the recipe below. Fill a pastry bag fitted with a plain round tip with the Nutella buttercream. Once the cookies are cool, pair them by size. Pipe some of the buttercream on the flat side of one cookie in each pair. Sandwich the whoopie pies together, pressing to nudge the filling to the edges.

Nutella Buttercream
3/4 cup (12 tablespoons) unsalted butter, softened
1/2 cup Nutella
1 teaspoon vanilla extract
1 tablespoon milk
1 cup confectioners' sugar, sifted

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and Nutella together until combined. Add the vanilla, milk and confectioners' sugar to the mixer bowl and beat on low speed until the powdered sugar is just about incorporated. Increase the mixer speed to medium and beat until the frosting is smooth.