Preheat your oven to 170ºC (340ºF) and line your cake pans with parchment paper.

Blend the unsalted pistachios into a fine powder, then sift with the all-purpose flour, baking powder, baking soda, and salt.

In a large mixer, cream together the butter and granulated sugar until light and fluffy for about 3-4 minutes.

Gradually add the eggs, mixing well after each addition.

Incorporate half of the dry ingredients, followed by sour cream, vegetable oil, and vanilla, mixing until smooth.

Fold in the remaining dry ingredients until just combined.

Divide the batter evenly between the prepared pans and bake for 20-23 minutes.

Allow the cakes to cool for about 10 minutes before transferring to a wire rack to cool completely.

Meanwhile, prepare the raspberry jam by combining the frozen raspberries, sugar, lemon juice, and vanilla in a saucepan. Simmer for about 8 minutes till slightly thickened.

Mix cornstarch with water to create a slurry and add it to the jam, stirring until the jam thickens.

For the buttercream, whip softened butter on medium speed until creamy, then gradually add powdered sugar and raspberry powder.

Pour in vanilla extract and milk, mixing until fluffy. Adjust consistency as needed.

Assemble the cake by leveling cooled layers and spreading jam and buttercream between layers.

Crumb coat the cake lightly then frost with remaining buttercream.

Decorate with fresh raspberries and chopped pistachios before serving.