If you’re not yet familiar with Yo Yos (otherwise known as Whoopie Pies, Black Moons, Gobs, or BFOs), you’re in for a real treat. Yo Yos yield a perfect cake-to-frosting ratio in an easy-to-devour format. A classic buttercream with a dash of lemon zest goes perfectly with the chocolate, offering a clean, crisp flavour complement to the dark, rich cake. If you’re looking for a chocolate dessert for a summer picnic, this is it. Really love buttercream? Double the recipe and add as much filling as your heart desires.

Makes twenty-five- 1 ½in (4cm) sandwich cookies

Cookies

  • ¾ cup (70g) Guittard Cocoa Rouge (Dutch processed unsweetened cocoa powder)
  • 2 cups (240g) all – purpose flour
  • ½ tsp baking powder
  • ½ tsp baking soda
  • ½ salt
  • ¼ cup (55g) unsalted butter at room temperature
  • 1 cup (200g) firmly packed light brown sugar
  • 1 large egg
  • 1 tsp vanilla extract
  • 1 cup (240ml) full-fat buttermilk

Lemon Buttercream

  • ½ cup (110g) unsalted butter, at room temperature
  • 1 1/3 cups(!60g) confectioners’ sugar
  • 2 tsp whole milk
  • 1 tsp vanilla extract
  • 1 tsp grated lemon zest

Method

To make the cookies: Preheat the oven to 350f (180c). Line two baking sheets with parchment paper.

In a medium bowl, whisk together the cocoa powder, flour, baking powder, baking soda, and salt. Set aside.

In a large bowl, with a hand mixture, beat together the butter and brown sugar until light and fluffy, about 3 minutes. Beat in the egg and vanilla until well combined. Alternately add the flour mixture and the buttermilk in four additions, beating on low speed until smooth and stopping to scrape down the bowl after eat addition.

Drop the dough by teaspoonful onto the prepared baking sheets, leaving 2 in (5cm) between the cookies; the cookies will spread as they bake. Make an even number of cookies, if you can, so you can sandwich them together.

Bake for 9 to 11 minutes, or until domed with a centre that spring back when lightly tapped. Cool the cookies on the baking sheets for 5 minutes before transferring to a wire rack to cool completely. (At this point, you can freeze the cookies for up to 2 months)

To make the lemon buttercream: In a medium bowl, using a hand mixture, beat together the butter and confectioners’ sugar until light and fluffy. Beat in the milk and vanilla until the buttercream is thick. Add the lemon zest and beat until combined.

Spread about 1 Tbsp buttercream onto the flat side of a cookie. Top with a cookie of similar size, flat side down, to sandwich together. Repeat until all the cookies are sandwiched. Let the Yo Yos sit at room temperature for 30 minutes to 1 hour before serving so the buttercream can set.

Store in an airtight container in the refrigerator for up to 4 days.