Preheat oven to 350°F (175°C).

Grease and flour two 9-inch cake pans.

Cream butter and sugar together in a large bowl until light and fluffy.

In a separate bowl, sift together flour, baking powder, and salt.

If using pudding mix, add it to the dry ingredients.

In another bowl, beat egg yolks and milk together.

Gradually add the wet ingredients to the creamed butter and sugar, alternating with the dry ingredients.

Mix well after each addition until just combined.

Stir in vanilla extract.

Pour batter evenly into prepared cake pans.

Bake for 20-25 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes before inverting them onto a wire rack to cool completely.

Ice as desired.