Pre heat the oven to 425 F and toast the shelled pistachios for 5 mins until they become fragrant.
Remove them from the oven, let them cool down and pulse in the food processor until finely ground. Do not over pulse them, or else they will turn into pistachio butter.
Reduce the oven temperature to 350 F.
Chop apricots into long thick slices. Grease the sides of an 8 inch pan with some butter. Take 3 tbsp melted butter in that baking pan. Sprinkle brown sugar all over the melted butter making sure, you are covering the pan. Arrange the apricots in circular pattern covering the butter/sugar. Sprinkle some ground cardamom. Leave it aside.
Combine all the dry ingredients in a bowl and leave it aside.
In a stand mixer, cream the butter and sugar until light and fluffy. Add the eggs one by one.
Add the almond or vanilla extract.
Add dry ingredients alternating with buttermilk until everything is mixed and combined. Turn off the mixer. Fold in the ground pistachios by spatula.
Add the cake mixture on top of the apricots. Bake for 40-50 minutes or until its done.
Let the cake cool for 10 minutes, not more than that otherwise its difficult to release it from the pan and then remove it carefully on a plate. If you need tap a couple of times. It came off easily for me. Let it cool completely and then slice before serving.
Garnish it with some more pistachios.
Serve it with ice cream, crème fraiche or whipped cream.