Preheat the oven to 325ºF. Grease the bottoms of two 9-inch cake pans or line the bottoms of the cake pans with parchment paper. Leave the sides of the cake pans ungreased.

Transfer the milk to a heat-proof glass measuring cup. Microwave for 30 to 45 seconds until bubbly and hot. Be careful not to scorch the milk.

Add the masala chai mixture and whisk to incorporate. Let stand for 5 minutes. Strain the milk through a sieve into a small bowl. Refrigerate until needed. See Note 3.

Add the sugar, 2 tablespoons at a time, mixing well after each addition. Add the spiced milk and mix until incorporated.

Sift the flour and baking powder into the egg yolks.

Beat the egg whites until stiff peaks form.

Fold the egg whites into the batter and stir gently until combined.

Divide the batter between the prepared cake pans. Transfer to the oven for 25 to 30 minutes or until the sponge cake is firm to the touch and a toothpick inserted into the center of the cake comes out clean.

Remove the sponge cakes from the oven and let cool for 5 minutes. Use a butter knife or a thin spatula to run around the sides and bottom of the pan to separate the cake from the pan. Flip the pan over onto a wire rack and lightly tap the bottom of the pan to release the cake if needed.

Allow the sponge cakes to cool for at least 1 hour. Once cool, you can wrap them in plastic wrap until you’re ready to begin the cake.

Beat the butter until smooth. Add the vanilla extract and chai masala. Add half the sifted powdered sugar and mix until combined, about 2 to 3 minutes. Add the rest of the powdered sugar and continue mixing until smooth, about 3 to 5 minutes. Add the heavy cream and continue mixing until a creamy consistency is met. Add more cream if needed.

Place a sponge cake on a cake stand and add a heaping tablespoon of the frosting. Smooth it out and place a second sponge cake on top. Add two heaping tablespoons of frosting on top and smooth it out with an offset spatula.

Use the remaining frosting around the sides of the cake, smoothing it out with an offset spatula. Cover the cakestand with a cloche and prepare the streusel.

Preheat the oven to 375ºF.

Place the pistachios in a gallon storage bag and use a heavy-bottomed pan or rolling pin to crush them. To the bag, add butter, flour, brown sugar, honey, garam masala, and a pinch of salt. Close the bag and use your hands to combine all of the ingredients into a crumbly mixture.

Pour the mixture onto a baking sheet. Transfer to the oven for 8 to 10 minutes. Remove and transfer to a bowl. Allow the pistachios to cool completely.

Place the streusel on top of the cake and use your hands to press it into a thick top layer that adheres to the frosting.

Slice the cake into pieces and enjoy!