Lemon Puff Pudding from C&H Sugar Bag

From C&H Sugar bag: Delicate cake on top of refreshing lemon sauce. This cake separates when you bake it.. a very light chiffony-cake on top and a delicious, though lumpy and translucent, "pudding" on the bottom. Good ratio of cake to pudding. I've made this cake following the recipe exactly, using fresh lemon and lemon zest, and it's absolutely delicious. I've also made it without fresh lemons.. using bottled lemon juice and omitting the lemon zest, which is still pretty good if necessary. I think this dessert would be better baked and served in six 6-oz ramekins (decrease cooking time), because the cake is sticky and so doesn't serve up cleanly. 9/5/2021 I adjusted the recipe a bit: decreased sugar and increased salt, changed up the order for easier mixing.

• Ready In: 1 hr 15 mins
• Serves: 6
• Yields: 1 1-1/2 qt pudding

Ingredients

• 3  large eggs, separated
• 1⁄2 teaspoon kosher salt
• 7⁄8 cup sugar, divided
• 3  tablespoons butter
• 1⁄4 cup lemon juice
• 2  teaspoons  grated lemon zest, lightly packed
• 1⁄4 cup flour
• 1 1⁄2 cups milk

Directions

1. Grease a round 1.5 qt or 1.6 liter casserole dish (I use the small round white Corning Ware). You'll also need a shallow pan for the water bath, to set the casserole dish in 1" hot water in the oven while baking.
2. Preheat oven to 325 degrees. Set water to boil in a tea kettle for the water bath.
3. Grate the zest of 1 large lemon, being careful to get only the yellow rind and not the bitter white pith. Then juice the lemon. Set aside.
4. Beat egg whites with salt until stiff, then gradually beat in 1/2 cup sugar. Set aside.
5. Cream butter with 3/8 cup sugar. Add eggs, lemon juice and zest, and beat well. Sift the flour over and whisk smooth. Gradually whisk in the milk. Fold in egg whites 'til well-combined.
6. Pour into greased casserole dish; set dish in shallow pan containing boiling water 1" deep. Bake in 325 degree oven for 50-60 minutes (go for 60 minutes if you can!), checking often in that last ten minutes to avoid burning top of cake.
7. Serve warm.