Lightly spray oil or grease a 9*13 glass pan. Now dust it all over with flour and keep it aside.
Add vinegar to the milk and mix well. It will look curdled and it is completely fine.
In a bowl whisk together sugar, yogurt, and milk. Whisk until smooth. Now add in oil. Whisk until completely combined.
In another bowl sift all dry ingredients except cardamom powder.
Add the dry mix to the liquid ingredient bowl in batches and whisk well until smooth and lump-free. Do not over-mix.
Transfer the batter to the prepared cake pan.
Bake in the oven.
Bake at 325 deg F for 20-25 minutes or only until a toothpick inserted in the center comes out clean.
Prepare the milk mixture.
While the cake is baking, boil the whole milk with saffron and cardamom. Once it comes to a boil, simmer it for 1 minute. Switch off the flame and keep it aside.
Now make the three types of milk mixture (tres leches) by combining warm milk with evaporated milk and condensed milk. Mix well.
Very important: Reserve 1.5 cups of this milk mixture for drizzling later on when eating. Drizzle at least 2 tablespoons of milk for each piece of cake.
You can add 1-2 drops of yellow food color if desired.
After the cake is baked, take it out of the oven. You are not supposed to flip it.
Add the milk mixture to the cake.
Just prick the top several times with a fork while it's still warm. Prick it really deep into the cake so that the milk that is poured in later seeps in well.
Pour the prepared milk mixture into the cake, ensuring it covers the entire cake evenly.
Initially, you will see a puddle of milk sitting on the cake, don’t worry it will all soak in within seconds.
If it doesn’t soak in that means you haven’t made enough holes or pricks. Simply make deeper pricks. Don’t worry it won’t be seen as the cake will be frosted.
Let it set in the fridge for at least one hour, before frosting.
After chilling in the fridge top it with prepared whipped cream frosting.
Make the whipped cream frosting.
To the bowl add chilled heavy cream, extract, and sugar, and whisk on high speed until it forms stiff/ firm peaks.
The whipped cream peaks should hold well on the balloon whisk. Do not over-whisk or it will turn into butter.
You can do fancy piping or simply spread an even layer of frosting on the cake then swirl it with a spoon to create texture as I did.
Garnish it with crushed pistachio, cardamom, and saffron if desired.
Let it sit in the fridge to set well for at least 2 hours before serving.
I prefer overnight as the flavor just gets better.
How to serve?
Serve the cake chilled just out of the refrigerator.
Gently place a small piece of cake on a plate. Now add some of the reserved milk mixtures all around the cake and just a little on the top to mimic Rasmalai.