Mix together ¼ cup of butter with the brown sugar, and then smear this around the base and ¼ of the way up the inside of an 8-inch cake pan.
Spread the pomegranate seeds out evenly in the cake tin on top of the sugar and butter mixture. Set the tin to the side.
Mix together the flour, baking powder, salt, ground cinnamon, ground ginger, ground cardamom, and ground nutmeg.
In a stand mixer or using a handheld electric whisk, beat together ⅔ cup softened butter with the granulated sugar for 3 to 4 minutes until it is pale and creamed.
Beat in the eggs one at a time, and then the vanilla extract.
Fold in half of the spiced flour mixture until just combined with the wet ingredients, then mix in the buttermilk. Finish off by folding in the remainder of the flour mixture.
Transfer the completed cake batter to the cake tin over the pomegranates, smoothing out the top.
Place the cake tin into the center of the preheated oven and leave it to cook for 40 to 45 minutes, until the top is golden and springs back to the touch.
Remove the cake from the oven and let it stand for 10 minutes, before carefully turning it out onto a plate or a cake stand.
Enjoy warm or cold, with ice cream or whipped cream as garnish.