Preheat the oven to 350 degrees F. Grease and flour two 8- to 9-inch cake pans and set aside. Mix the flour, baking powder and salt together in a small bowl. Using an electric mixer, cream the butter and sugar together until light and fluffy, 3-5 minutes. Then add 2 teaspoons of vanilla.
Crack the eggs into a measuring pitcher. Then with the mixer running, alternate adding the eggs and flour mixture until just combined. Scrape the bowl and mix again for 30 seconds. Divide the cake batter evenly between the two pans and bake for 20 minutes, until golden on top.
Cool for 10 minutes, then flip the cakes out of the pans onto wax paper lined plates. Meanwhile, whisk the evaporated milk, condensed milk, espresso and remaining 1 teaspoon of vanilla together. Set aside.
Poke both cakes with a fork thoroughly, to help the espresso mix absorb. Slowly pour half the mixture over each cake and allow them to sit and soak it all up while you make the whipped cream.
Using a clean bowl and electric mixer, whip the heavy cream with 1/4 cup sugar until firm peaks form. To assemble: carefully flip one of the cake layers onto a platter with a shallow rim, and peel off the wax paper. Scoop about half of the whipped cream onto the cake and spread evenly. Then carefully flip the second cake layer on top and remove the wax paper. Spread the remaining whipped cream on the top and sprinkle with cocoa powder. Refrigerate until ready to serve.