In a large bowl, beat the eggs, sugar and vanilla until thick and pale yellow, about 4 minutes.
Combine the flour, baking powder and salt; add to egg mixture and beat just until combined.
In a saucepan, bring milk and butter to a boil, stirring constantly. Add to batter and beat until combined. Pour into a greased 9-inch cast iron skillet.
Bake for 30-35 minutes or until a toothpick inserted near the center comes out clean. Remove cake from oven and turn the temperature up to broil.
Combine topping ingredients and spread over warm cake. Broil 4 inches from heat until lightly browned, about 3-4 minutes.
Notes
Can be baked in a 9-inch round cake pan instead. Do not use a glass baking dish as glass cannot withstand the temperature of the broiler.