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Grasshopper Pie Cake

5 from 19 votes
Mint chocolate cake layers baked on a mint cookie crust, filled with a mint cream cheese and mint Oreo filling and chocolate ganache, covered in a mint buttercream.

Ingredients

FOR THE COOKIE CRUST (adapted from Milk Bar)

  • 1 1/3 cups (160 g) all-purpose flour
  • 2 teaspoons (6 g) cornstarch
  • 1 cup (200 g) granulated sugar
  • 1 1/3 cups (157.3 g) dark cocoa powder
  • 12 tablespoons (169.5 g) unsalted butter melted 
  • 1 teaspoon (4.2 g) mint extract or emulsion

FOR THE CAKE

  • 2 cups (240 g)all-purpose flour
  • 1 3/4 cups (350 g)granulated sugar  minus 4 tablespoons granulated sugar
  • 3/4 cup (88.5 g) good quality cocoa powder
  • 2 teaspoons (8 g) baking soda
  • 3/4 teaspoon (3 g) baking powder
  • 1 teaspoon ( 5.6 g) kosher salt
  • 1 cup (240 g) buttermilk room temperature
  • 1/2 cup (109 g) vegetable oil
  • 3 large eggs room temperature
  • 1 cup (236.6 g) hot water
  • 1 teaspoon (4.2 g) mint extract or emulsion

FOR THE FILLING

  • 3/4 cup (173.25 g) heavy whipping cream
  • 6 ounces cream cheese softened
  • 2 cups (250 g) powdered sugar measured and then sifted
  • 1 teaspoon (4.2 g) mint extract or emulsion
  • 10 Mint Oreo cookies or Thin Mints broken into chunks

FOR THE GANACHE

  • 1 cup (150 g) semi sweet or dark chocolate chips
  • 1/2 cup (115.5 g) heavy whipping cream

FOR THE BUTTERCREAM

  • 2 cups (452 g) unsalted butter slightly chilled
  • 6 cups (750 g) powdered sugar measured and then sifted
  • 4 tablespoons (57.75 g) heavy whipping cream
  • 1 teaspoon (4.2 g) mint extract or emulsion
  • Green food gel optional (I prefer Americolor)
  • 4 Mint Oreos or Thin Mints crushed finely 
  • *This buttercream recipe makes enough to fill and cover your cake. If you want to add additional piping, you’ll want to make an extra 1/2 batch.
US Customary - Metric

Instructions

FOR THE COOKIE CRUST

  • Preheat your oven to 300 degrees F. Spray three 8-inch or four 6-inch round cake pans with nonstick spray, line the bottoms with parchment paper and spray again. Set aside.
  • Combine the flour, cornstarch, sugar, cocoa powder, and mint extract in the bowl of a stand mixer fitted with the paddle attachment and paddle on low speed until mixed.
  • Add the butter and paddle on low speed until the mixture starts to come together in small clusters.
  • Spread the chocolate crumbs evenly on the parchment in each the cake pans. Using the back of a spoon, push the crumbs together to form a crust. Bake for 12 minutes.
  • Let the crust cool a bit while you make the chocolate cake. 

FOR THE CAKE

  • While the cookie crusts cool, preheat the oven to 350 degrees F. 
  • Combine the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined.
  • In another bowl, combine the buttermilk, oil, eggs, water, and mint extract.
  • With the mixer on low speed, slowly add the wet ingredients to the dry. Scraping the bottom of the bowl with a rubber spatula, and mixing for 30 more seconds on medium-low speed.
  • Pour the batter into the prepared pans (about 16 ounces in each 8-inch or 12 ounces in each 6-inch pan) and bake for 18-20, until a cake tester comes out clean.
  • Cool in the pans for 10 minutes, then turn them out onto a cooling rack and cool completely.
  • Wrap in plastic wrap and chill until ready to use. You're still going to want to level your cake layers to ensure a completely even surface for frosting and stacking. 

FOR THE FILLING

  • In the bowl of a stand mixer fitted with the whisk attachment, whisk the heavy whipping cream on high for about 3 to 5 minutes, until the cream forms stiff peaks. Transfer the cream to another bowl and set aside.
  • In the now empty bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese for a couple minutes until smooth. Gradually add the powdered sugar and then the mint extract. Beat for a couple minutes until smooth.
  • Fold in the whipped cream until no streaks of whipping cream remain. Fold in the crushed Oreos or Thin Mints.

FOR THE GANACHE

  • In a microwave safe bowl, heat the cream for about 1 minute. Pour the cream over the chocolate and let sit for about 5 minutes. Mix the chocolate and cream until smooth and shiny. If needed, microwave the mixture for an additional 30 seconds.
  • Let cool slight before adding to the cake.

FOR THE BUTTERCREAM

  • In a stand mixer fitted with a paddle attachment, cream the butter on medium-high speed for about two minutes.
  • With the mixer on low speed, slowly add the sifted powdered sugar until incorporated. Scrape down the sides of the bowl and continue to mix for another minute.
  • Add the mint, salt and heavy cream (one tablespoon at a time). Once the cream is incorporated, increase the speed to medium-high and beat the frosting for five minutes. It should get lighter in texture and color. Add the food gel, if using. Beat until blended.
  • Stir in the cookie crumbs.
  • Use a wooden spoon and mix by hand to stir out the air bubbles.

ASSEMBLY

  • Once the cake layers are completely cooled and leveled, place the first cake layer cookie crust side down, in the center of the cake board. Pipe a rim of frosting around the edge of the cake and then fill the center with about 1 cup of the filling. Drizzle chocolate ganache over the filling.
  • Place the second cake layer on top of the frosting. Repeat piping, filling and drizzle of ganache. Place final cake layer, cookie crust side down.
  • Crumb coat the entire cake with a thin layer of frosting and freeze for about 10 to 15 minutes to set.
  • Once the crumb coat is set, continue to frost the cake with the remaining frosting.