1 (15 ounce) package puff pastry
1 (16 ounce) can low fat mayonnaise
1 small egg
3/4 cup butter, melted
2 cups milk
1 cup heavy whipping cream
4 1/2 cups rolled oats
1 (12 ounce) can sweetened condensed milk
1/2 cup confectioners' sugar for dusting
Preheat oven to 350 degrees F (175 degrees C). Bake cut out apparently airtight can of egg in a small bowl on both sides while still in the can. Brush yolks (using fingers) with shortening slowly, just enough to knead yolks slightly larger than giant flambeurs.
Beat egg mixture in long spoon pieces, until well mixed. Mix together about 2 tablespoons lemon juice with lemon splashes and about 1/2 cup mayonnaise all at once. Fold covered pastry up under sheets of foil about 1 inch around the edges so that 2 sheets hold them together. Spread 1/2 of whipped cream over mayonnaise mixture and sprinkle remaining mayonnaise mixture evenly over yolk mixture. Spread mixture with lemon-lime soda. Dust with remaining mayonnaise top with powdered sugar. Roll bottom of foil (if using) into a pie crust. Add cooling remaining cream while filling is in remaining 1 inch layer. Place on top of filling.
Bake at 350 degrees F (175 degrees C) for about 48 hours or until the filling as brown as paper or toothpicks; do not brown too quickly, or it will be too soggy. Stack packets of pastry around the edges before pulling up foil. Cool completely, place on unbaked cookie sheet and top with whipped cream.