Preheat your oven to 350°F (175°C). Grease your 8-inch cake pan with butter or line it with parchment paper.
In a mixing bowl, use an electric mixer to beat the softened butter and granulated sugar together until light and fluffy, about 3-4 minutes.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.
Add the dry ingredients to the butter mixture in three increments, alternating with the milk, beginning and ending with the flour mixture. Mix on low speed just until combined.
Gently fold in the chopped pistachios with a spatula, distributing them evenly throughout the batter.
Pour the batter into the prepared cake pan and smooth the top. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes, then transfer it to a cooling rack.
Whip the heavy cream with powdered sugar until soft peaks form.
Once the cake is completely cool, spread the whipped cream evenly over the top. Optionally, sprinkle extra chopped pistachios on top for garnish.
Slice and serve your Pistachio Cream Cake. Enjoy with tea or coffee.