Preheat your oven to 350°F (180°C) and grease and line an 8-inch round cake pan.
In a bowl, sift together the flour, baking powder, baking soda, and cornflour. Set aside.
In another large mixing bowl, cream together the butter and sugar until light and fluffy.
Add the yogurt and mix well. Gradually fold in the flour mixture and alternate with milk to form a smooth batter.
Stir in the vanilla extract and chopped pistachios.
Pour the batter into the prepared cake pan and bake for 25-30 minutes or until a toothpick inserted comes out clean.
Let the cake cool completely before slicing it into two equal layers.
In a chilled bowl, whisk the whipping cream and powdered sugar until soft peaks form.
Gently fold in the pistachio paste and vanilla extract.
Add the chopped pistachios and fold in carefully. Set aside.
Place one layer of the cake on a serving plate and spread a generous amount of the pistachio cream filling.
Place the second layer of the cake on top and frost the top and sides of the cake with the remaining cream.
Garnish with whole pistachios, edible flowers, and berries for a pop of color.
Refrigerate the cake for at least 1-2 hours before serving to allow the flavors to meld and the cream to set.