Tea biscuit attempt number four - they finally taste delicious

It is time to chronicle attempt number four in the continuing saga of finding a recipe for tea biscuits similar to those made by Termini's in Philadelphia.  I'm happy to say, attempt number four's tea biscuits are good!  They are the first I've made that I'm going to eat more than one.  Okay, I'm going to have several.  The taste is excellent.  The texture is good.  There is still something missing, but I can't figure out what it is yet.

To recap, Termini's tea biscuits are sweet, not savory.  I've never had anything like them outside of the Philadelphia/South Jersey area.  I made up the recipe myself, building on the recipe I invented for tea biscuit attempt number three.  This time the dough was much easier to work with.  It was a little sticky, but I could still work it with my floured hands.  I could cut it easily with the biscuit cutter, too.  I upped the amount of sugar and vanilla extract.  I cut the amount of whole eggs and substituted egg yolks.  I think these factors made a huge difference.  I left out the raisins again, but those would be an easy addition at the end.

I'm very pleased with how these turned out.  They may not be Termini's tea biscuits exactly, but they are good in their own right.  I'd make them again.  Don't just take my word for it.  I gave them to my father, for whom I've been on this quest to find the recipe.  He ate one.  He said what a great job I did.  Then he immediately ate a second one.

I got about a dozen tea biscuits out of this recipe.  Yes, those are tablespoons of baking powder and vanilla extract; that is not a typo.  I usually only put one cookie sheet in the oven at a time.  After the first one went in the oven, I balled up the dough and wrapped it in wax paper to throw in the refrigerator until it was time to reroll it for the second sheet's biscuits.

5 cups flour
a large pinch of salt
1 stick butter, cut into small pieces and chilled
1 whole egg (plus an additional egg for the egg wash)
4 egg yolks
1 cup milk
1 1/2 tbs baking powder
1 cup sugar
2 tbs vanilla extract

1.  Preheat oven to 475 degrees.
2.  Combine flour, sugar, salt, and baking powder in the bowl of a food processor.  Pulse to mix together.  Add the chilled butter and pulse to cut the butter into the flour mixture.
3.  In a medium bowl, whisk milk with one whole egg and four egg yolks.  Make sure the eggs are thoroughly mixed with the milk.  Stir in the vanilla extract.
4.  Transfer the flour mixture to a large bowl.  Make a well in the center and pour the milk mixture into the well.  Use a fork to bring the dough together.
5.  Turn the dough out onto a lightly floured surface and knead it together.  Roll it out or pat it out with floured hands to about 3/4 of an inch thick.  Use a three inch biscuit cutter to cut out biscuits and transfer to baking sheets lined with parchment paper.
6.  Beat the final egg for an egg wash.  Brush the top of the biscuits with the egg wash and bake for 12 minutes, until the tops are browned and the biscuits are baked through.  Transfer biscuits to a wire rack to cool.