Preheat oven to 350°F. Spray the 9x13 glass baking dish with non-stick cooking spray.
In a medium bowl, combine flour, baking powder, and salt.
Separate the eggs into two separate bowls.
Add 3/4 cup sugar to the bowl with the egg yolks and mix on high speed until yolks are pale yellow. Add the 1/3 cup milk and vanilla and stir to combine.
Pour the egg yolk mixture over the flour mixture and stir gently just until combined. (don't over-mix)
Use electric beaters to beat the egg whites on high speed. Gradually add the remaining 1/4 cup of sugar as you mix and continue beating until stiff peaks.
Fold egg whites into the batter gently, just until combined. Pour batter into prepared pan. Make sure to smooth it into an even layer.
Bake for 25 to 35 minutes, or until a toothpick inserted in the center of the cake comes out clean. Remove from the oven and allow cake to cool completely.
Combine the evaporated milk, sweetened condensed milk, and whole milk in a small bowl. Once the cake has cooled use a fork to poke holes all over the top of the cake.
Slowly pour the combined milks over the the top of the cake, making sure to pour near the edges.
Refrigerate the cake for at least 1 hour or overnight, to allow the cake to soak up the milks.
In the meantime, whip the heavy cream, sugar and vanilla until stiff peaks. Smooth over the top of the cake and sprinkle the top with cinnamon. Serve cold and enjoy!