Preheat the oven to 350°F (180°C). Grease and flour a cake pan

In a large bowl, cream together the butter and sugar until well combined

Add the egg yolks, whiskey, and vanilla extract to the butter mixture, mixing until thoroughly blended

Gradually incorporate the sifted all-purpose flour along with the baking powder and salt, alternating with the milk. Mix until smooth

In a separate bowl, beat the egg whites until stiff peaks form. Gently fold them into the batter

Pour the batter into the prepared cake pan

Bake in the preheated oven for 1 hour, or until a toothpick inserted into the center comes out clean

Unmold the cake while still warm