Preheat the oven to 350 F, and position a rack in the center of the oven. Lightly spray an 8-inch round cake pan with non-stick baking spray. (You can also use a 9-inch round pan, but the baking time will be about 5-10 minutes less since the cake will be thinner.)

In a large bowl, sift together the flour, sugar, baking powder, salt and cardamom, and whisk until combined.

Add the egg, egg white, buttermilk, melted butter, oil and vanilla, and whisk for 10-15 seconds, just until combined. Pour the batter into the prepared pan.

Bake for about 25-30 minutes, until the top of the cake springs back when lightly touched and a cake tester comes out clean. Set the pan on a wire rack, and cool for 30 minutes.

Run a knife around the edges of the cake, turn the warm cake out of the pan, and set it on a serving plate. Slice a small portion of the browned, domed top off the top of the cake, which helps to open up the cake crumb to absorb the milk. Or, you can just use a wooden skewer or chopstick to poke the cake full of holes.

Brush or drizzle the reserved ⅓ cup milk over the cake. Cover the cake with plastic wrap, and refrigerate until completely cooled, about 1 ½ hours.

In the bowl of your stand mixer fitted with the paddle attachment (or using a hand held electric mixer), beat the cream cheese, powdered sugar, cocoa powder and vanilla for several minutes, until smooth.

Stream in the cream, scraping up the mixture from the bottom. Beat on medium speed for several minutes until it becomes thick and fluffy enough to hold its shape.

Frost the cake with the whipped cream. Serve immediately, or keep refrigerated in an airtight container until ready to serve.