Preheat the oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.

In a bowl, mix together flour, baking powder, and salt. Set aside.

In another bowl, beat eggs until thick. Gradually add sugar, and continue beating until the mixture is light and fluffy. Stir in vanilla extract.

Gently fold in the dry ingredients. Mix in boiling water and melted butter until well combined.

Pour the batter into the prepared pan and bake for 30-35 minutes.

For the topping, combine brown sugar, cream, butter, and coconut in a saucepan. Bring to a boil, then remove from heat.

Spread the topping over the hot cake and broil until bubbly and golden brown.