Creating the Raspberry Pistachio Cake is straightforward if you follow these steps:

1. Preheat your oven: Set your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. Cream the Butter and Sugar: In a large bowl, beat the softened butter and granulated sugar together until light and fluffy.
3. Add Eggs and Vanilla: Mix in the eggs, one at a time, ensuring each is well incorporated. Then add the vanilla extract.
4. Combine Dry Ingredients: In another bowl, whisk together the flour, baking powder, and salt.
5. Alternate Dry and Wet Ingredients: Gradually add the dry ingredients to the butter mixture, alternating with the whole milk. Begin and end with the dry ingredients, mixing until just combined.
6. Fold in Raspberries and Pistachios: Gently fold the raspberries and chopped pistachios into the batter, being careful not to crush the fruit.
7. Divide the Batter: Pour the batter evenly into the prepared cake pans.
8. Bake the Cake: Bake in the preheated oven for 35-40 minutes or until a toothpick inserted in the center comes out clean.
9. Cool the Cakes: Remove from the oven and let the cakes cool in the pans for 20 minutes. Then transfer them to wire racks to cool completely.
10. Prepare the Frosting: In a bowl, beat 4 tablespoons of softened butter with 2 cups of powdered sugar. Gradually add heavy cream until you achieve a smooth, spreadable consistency.
11. Frost the Cake: Once the cakes are completely cool, place one layer on a serving platter. Spread frosting over the top. Place the second layer on top and frost the top and sides of the cake.
12. Garnish: Decorate with fresh raspberries and sprinkled chopped pistachios for a beautiful finish.

Following these steps will guide you in creating a Raspberry Pistachio Cake that not only tastes amazing but also looks stunning.