Preheat oven to 350 degrees Fahrenheit. Combine the eggs, sugar, and vanilla extract in an electric mixer with the whisk attachment. Mix on high for 10 minutes until it is pale yellow and & fluffy.*You can use an electric hand mixer as well, but it may take a little longer.
Meanwhile, combine the flour, baking powder, and salt. Sift a few times to incorporate evenly throughout.
After 10 minutes of mixing, reduce the speed to low and slowly add in the sifted flour mixture and milk, alternating a couple of times. Once you no longer see any flour, stop mixing. It should be thick enough to make distinct ribbons and you should see air bubbles in the mixture.
Pour into a 9x13 baking or casserole dish.
Bake at 350 degrees Fahrenheit for about 25 minutes. You'll know the cake is done when you stick a toothpick through the center and it comes out clean. Let it cool completely.
Meanwhile, mix together the three milks mixture- sweetened condensed milk, heavy cream, evaporated milk, and a splash of brandy (I used Hennessey).
Poke a bunch of holes into the cake with a toothpick or fork. The more the better! Then slowly pour the milk mixture over the cakes, letting it fully absorb the milk before adding more.
Cover with plastic wrap and let it set in the fridge for at least 8 hours. One or two days ahead is even better so the cake has time to soak up as much of the milk as possible.
The next day, combine heavy whipping cream and powdered sugar until soft peaks form. Careful not to overwhip- it will become grainy. If that happens, you can just add a couple more tablespoons of heavy cream and whip again.
Evenly spread the whipped cream on top of the cake, then sprinkle over any flavored powders (if using). You don't have to use any, but cinnamon is pretty common and I think pumpkin spice is great for the holidays.
I recommend refrigerating again before serving. At least another couple of hours- trust me it really makes a difference! You can keep this cake in the fridge for 3-5 days.