Preheat your oven to 350°F (175°C) to ensure even baking.
Grease your 9x13 inch baking pan with melted butter or non-stick spray.
In a large mixing bowl, beat the 4 eggs and 1 cup of sugar together until thick and pale, about 5 minutes.
Add 8 tablespoons of melted butter and 1 teaspoon of vanilla extract and mix well.
Sift in 1 cup of flour and gently fold until just combined, being careful not to over-mix.
Slowly pour in 2 cups of lukewarm milk, stirring gently until smooth. The batter will be thin.
Pour the batter into the prepared pan and bake for 40-50 minutes, or until golden brown and a toothpick comes out clean.
Allow the cake to cool in the pan for about 10-15 minutes before dusting with powdered sugar and slicing.
