Preheat oven to 350 degrees F. Grease the bottom of a 8-inch square baking pan.

Add milk to a saucepot and heat over medium heat. Once milk begins to simmer, remove from heat and add tea bags. Steep tea for 30 minutes. Remove tea bags, squeezing as much liquid from the tea. Set aside ¼ cup of the infused milk. Measure the remaining milk, you should have ½ cup remaining. If you don't have enough, add enough milk to measure ½ cup. Add evaporated milk and sweetened condensed milk, whisking until well combined. Set aside.

Make cake batter. Sift flour, baking powder, and salt in a medium bowl. Set aside.

In a large bowl, beat egg yolks with 6 tablespoons sugar (75 grams) until mixture is pale yellow. Add vanilla and reserved ¼ cup infused milk, mixing until well combined. Add sifted flour mixture, stirring just until combined.

Place egg whites in a large bowl and whip until soft peaks form. Slowly add the remaining 2 tablespoons sugar (25 grams) while constantly beating the egg whites. Continue to whip until stiff peaks form.

Add ⅓ of the whipped egg whites to the cake batter, stirring to combine. Fold in the remaining egg whites until combined. Carefully pour cake batter into prepared cake pan. Bake cake for 18-20 minutes or until a toothpick inserted in the center comes out clean. Remove from the oven and let cool completely.

Prick the cake with a fork evenly throughout. Slowly add the milk mixture, allowing the cake to soak in some of the liquid before adding the remaining. Cover the cake and chill in the refridgerator for at least 1 hour or overnight.

When ready to serve, make the chocolate whipped cream. Whip heavy cream until soft peaks form. Add powdered sugar and cocoa powder and whip until stiff peaks form. Spread chocolate whipped cream on tres leches cake. Sprinkle grated chocolate on top if desired and serve.