Mango-Pistachio Crunch Cake (Mom's Birthday Cake)

Today is my mom's birthday, and what sweeter way to celebrate than with a cake made just to suit her palate. 

My mom loves mango, pistachios, saffron, and cardamom, and I've made her birthday cake using these ingredients in previous years.  But this year, I wanted to shake up this cake, and this is what I came up with.

Although I'm not a huge fan of Momofuku Milk Bar - I think everything there is far too sweet - I do think that Christina Tosi is quite clever in the kitchen and has come up with some truly unique components and techniques.  One of my favorites is one that's used in her cakes (which, unfortunately, are no longer sold by the slice): crunchies.

Reminiscent of the middle layer of crunchies in ice cream cakes from childhood birthday parties, these crunches made with nuts and puffed rice cereal add a great textural element to what's normally otherwise an all-soft affair.The pistachio crunch in this cake was a huge hit and is something I plan to incorporate into more cakes in the future.  And the cornstarch-thickened custard is another easy but different filling that provided a break from the usual buttercream frosting between cake layers that is standard (albeit tasty).

None of the elements of this cake are difficult to make.  Although they do require a little extra time, they're absolutely worth it, especially when you're making a cake to celebrate someone as wonderful as my mom.

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Mango-Pistachio Crunch Cake

makes one three-layer 8" cake - serves 10-12

For the mango custard

1 cup whole milk

1 cup Alphonso mango puree*

3 tablespoons cornstarch

For the cardamom cake

2 ½ cups + 2 tablespoons all-purpose flour

1 tablespoon baking powder

¼ teaspoon salt

¼ teaspoon freshly ground cardamom (use 1/8 teaspoon more if using pre-ground)

1 ½ sticks (6 ounces) unsalted butter, room temperature

¾ cup granulated sugar

¾ cup turbinado sugar

3 large eggs

1 ½ cups whole milk

1 teaspoon vanilla

For the pistachio crunch
1 cup shelled unsalted pistachios

2 tablespoons turbinado sugar

1 ½ teaspoons canola oil

1 cup puffed rice cereal

For the saffron-mango meringue buttercream frosting 

4 large egg whites

¾ cup granulated sugar

Large pinch saffron threads

2 sticks (8 ounces) unsalted butter, room temperature

3 tablespoons Alphonso mango puree*

For assembling the cake

¼ cup whole milk

*Note: I use Ratna brand sweetened Alphonso mango puree, which is available at Indian grocers and online

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Make the mango custard

Put the cornstarch in a small bowl and set aside.

Heat the milk in a small saucepan set over medium heat.  When the milk is steaming, add ¼ cup of milk to the cornstarch and whisk well to combine.  Transfer this mixture back to the saucepan and add the mango puree.  Cook over medium heat until the mixture is bubbling and has thickened slightly, about 5 minutes.

While the custard is cooking, set a fine-mesh sieve over a large non-reactive bowl.

Strain the custard into the bowl and let cool at room temperature until the custard is cool to the touch.


Make the cake

Heat oven to 350 F.  Position the racks in the upper and lower thirds of the oven.  Lightly grease three 8” round cake pans.  Line each pan with parchment, grease and flour the parchment, and set aside. 

Add the flour, baking powder, salt, and cardamom to a medium bowl and whisk to combine.

Put the butter, granulated sugar, and turbinado sugar in the bowl of a standing mixer and beat on medium speed until light and fluffy, about 3 minutes, making sure to scrape down the sides of the bowl every so often.  Add the eggs one at a time, beating well after each addition and scraping down the sides of the bowl before adding the next egg.

Add ¼ of the flour mixture and mix on low speed until barely incorporated.  Scrape down the sides of the bowl and add 1/3 of the milk.  Mix until combined.  Repeat this process, ending with the flour mixture.

Divide the batter between the three pans and rap them against the counter to remove any air bubbles.  Bake until the tops of the cakes spring back lightly when pressed and a toothpick comes out clean, about 22 minutes, making sure to rotate the position of the pans hallway through baking.

Let the cakes cool for 20 minutes, then run an offset spatula or thin knife around the edges of the pans and turn the cakes out onto cooling racks.  Let the cakes cool right side up.


Make the pistachio crunch

Leave the oven at 350 F. 

Spread the pistachios in a pie plate or small baking sheet.  Toast the nuts until they are fragrant, about 12 minutes.  Transfer the nuts to a plate to cool.

Transfer the nuts to the bowl of a mini chopper.  Add the turbinado sugar and process until a fine powder forms and starts to form a paste.  Scrape down the sides of the bowl, add the canola oil, and process to form a smooth paste.

Transfer the paste to a bowl, then gently mix in the rice cereal.


Make the saffron-mango buttercream frosting

Follow my directions for Swiss meringue buttercream frosting with the following modifications:

• Crumble the saffron into the egg white-sugar mixture, then place the bowl over the double boiler.
• After all the butter has been added and the frosting has come together, add the mango puree one tablespoon at a time, mixing well and scraping down the sides of the bowl between each addition.

Assemble the cake

If the tops of the cakes are domed, use a large serrated knife to level the tops.

Place a small dollop of frosting on a 9” round cake board.  Place a cake layer on the board with the bottom side facing up and gently press down to ensure that it sticks to the board.

Transfer 1 cup of the frosting to a piping bag fitted with a ¼” round tip and set aside.  [If you want to pipe a decorative border around the top and bottom edges of the cake, make sure to put a coupler in the piping bag so you can later switch out the round top for a star tip.]

Brush the cake layer on the board with milk and wait 10 seconds for it to be fully absorbed.  Spread a thin layer of the frosting on the cake, making sure it reaches the edges.  Pipe a ring of frosting around the edge of the cake, then pipe another ring directly on top of the first one.

Spread half of the mango custard on the cake layer.  Top the custard with half of the pistachio crunch. [Note: the crunch is more chunky/crumbly then spreadable, so use your hands to distribute it evenly over the custard.]

Place another cake layer on top, making sure the bottom side is facing up.  Very gently press down to make sure it adheres to the ring of frosting around the edge of the layer below it.  Repeat the soaking, frosting, and filling process as with the previous layer, then place the final layer on top, again with the bottom side facing up.

Spread the remaining frosting over the top and sides of the cake.  [If you’re a perfectionist, first apply a crumb coat, chill the cake, then apply the final layer of frosting.  I usually do that, but because I was running low on time (and fridge space), I didn’t do that with this cake and it came out just fine.] 

If you want, use a star tip to pipe a border of stars around the top edge of the cake as well as at the bottom edge where the cake meets the board.