Step 1

Preheat oven to 325 degrees F. Grease or spray a 9-inch round deep dish pie plate or cake pan.

Step 2

In the bowl of an electric mixer, whip egg whites with the salt until they form stiff peaks.

Step 3

Remove from the bowl to another container and in the same bowl place egg yolks with sugar, water and vanilla. Beat until well mixed and light colored, about 1 minute. With the machine running, add the melted butter and beat until incorporated.

Step 4

Add the flour and beat another minute until well mixed, then, with machine running, add the milk slowly until mixture is well combined.

Step 5

Use a wide rubber spatula to fold the whites and batter together. The final batter will be somewhat runny and should be well mixed, but small lumps of the egg whites may remain.

Step 6

Spoon into the prepared bake dish and bake for one hour until top is golden brown. Gently shake the pan it should be firm with only a slight jiggle in the center; if it moves too much, continue to bake another 5 10 minutes.

Step 7

Cool on a wire cooling rack for at least an hour before serving. Serve while just slightly warm or it may be chilled and served cool. Sprinkle with powdered sugar before cutting and serving in wedges.