Prepare the pan & oven: Preheat your oven to 350°F (180°C). Line a 9-inch square baking pan with parchment paper or grease it well. Set aside.
Mix the dry ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
Cream the butter and sugar: In a large mixing bowl, beat the softened butter and sugar together until light, pale, and fluffy. This may take about 2–3 minutes using a hand or stand mixer.
Add the wet ingredients: Beat in the eggs, one at a time, followed by the vanilla extract, mixing just until combined.
Alternate dry ingredients and buttermilk: Sift in half of the dry mixture and mix on low speed. Then add half of the buttermilk and mix until just combined. Repeat with the remaining flour mixture and buttermilk.
Add pistachios: Fold in the finely crushed pistachios using a spatula until evenly distributed.
Bake the cake: Pour the batter into your prepared pan and smooth the top. Bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 5 minutes, then carefully remove it and transfer to a wire rack to cool completely.
Make the Frosting: In a bowl, beat the softened butter until creamy. Add the cream cheese, pistachio paste, and icing sugar, and beat until smooth and fluffy. If the frosting feels too soft, chill it for 15–20 minutes before using.
Decorate: Once the cake is completely cool, spread the frosting evenly on top. Sprinkle with extra crushed pistachios for a beautiful finish. Refrigerate the cake for at least 3 hours before slicing and serving—this helps the flavors develop and the frosting set.
Video
Notes
Storage: Keep the frosted cake in an airtight container in the refrigerator for up to 4–5 days.
Buttermilk: This helps make the cake moist and tender thanks to its acidity. If you don’t have buttermilk, you can make a substitute: mix 1 cup milk with 1 tablespoon lemon juice or vinegar and let it sit for 5–10 minutes.
Ground Pistachios: If you can’t find store-bought ground pistachios or pistachio flour, it’s very easy to make at home! Simply place raw, unsalted shelled pistachios in a food processor or high-speed blender and pulse until finely ground. Be careful not to over-blend, or you’ll end up with pistachio butter. I demonstrate exactly how to do this in the video tutorial, so be sure to watch it!
Pistachio Paste: For the best flavor, use a high-quality 100% pistachio paste. If you prefer homemade, check out my homemade pistachio paste recipe. Avoid pastes with added sugar or oils, as they can affect the frosting's texture.
Pan Size: This recipe is written for a 9-inch square pan, but it also works beautifully in a 9-inch round cake pan or a 9x13-inch rectangular pan for a thinner sheet-style cake. Just keep an eye on the baking time—it may be slightly shorter in a larger pan.
Watch the Video: Want to see the full process? Don’t forget to watch the step-by-step video tutorial linked below the recipe card.
FAQs: Scroll down below the recipe card for answers to common questions.