Preheat your oven to 350°F. In a large mixing bowl, combine the flour, baking powder, and salt. In another bowl, beat the eggs and sugar until light and fluffy. Gradually mix in the dry ingredients and vanilla, ensuring a smooth batter. Pour into a greased 9x13 inch tray and bake for 25-30 minutes, until golden-brown and a toothpick inserted comes out clean.
While the cake cools, blend the mango chunks, yogurt, milk, and cardamom powder until smooth. If the mixture is too thick, strain it through a fine mesh sieve to achieve a silky consistency.
In a medium bowl, whisk together the sweetened condensed milk, evaporated milk, plain milk, and 1 cup of the mango lassi. The combination creates a luscious soak for the cake.
Once the sponge cake has cooled completely, use a skewer or fork to poke holes all over the top. This allows the three-milk mixture to penetrate deeply into the cake.
Gradually pour the three-milk mixture over the cake, allowing it to soak in before adding more.
Cover the soaked cake with plastic wrap and refrigerate for at least 4 hours, preferably overnight.
In a large mixing bowl, whip the heavy cream until stiff peaks form. Gradually fold in the remaining mango lassi.
Carefully spread the mango whipped cream over the top of the chilled cake, and garnish with fresh mango slices or chunks.