First prepare the shortcakes.
In a large mixing bowl, mix together the flour, salt, sugar and baking powder.
Cut in the softened butter, either using a pastry blender or two knives, until it looks crumbly.
Gradually add the milk, stirring just until dough forms. Form into a ball and wrap in plastic wrap and refrigerate until dough is chilled.
Remove from refrigerator and using a lightly floured rolling pin, roll out until 1/4 inch thick.  Using a very sharp knife, cut into 1 inch by 3 inch rectangles.
Arrange on a non-stick baking sheet and bake until golden 10-15 minutes. 
Remove from pan and cool on wire rack.

While shortcakes are cooling prepare the vanilla sauce.
In a medium mixing bowl, whisk together milk, yolks, sugar and vanilla.
Place into top of double boiler and cook until the temperature reaches 185 degree F (heated through).
Using a sieve, strain the sauce and let cool.

Prepare the watermelon cutting it into rectangles the same size as the shortcakes, 1 inch by 3 inches.




Plating

Place two shortcakes on the plate roughly 2 1/2 inches apart, parallel to one another. 
Next take two pieces of watermelon and place them perpendicular to the shortcakes (refer to photo). Repeat until you have four layers of each, alternating shortcake, watermelon.
Top with a dollop of whipped cream.

Note: If you want additional color on the top, add blueberries or blackberries for a nice contrast.