Preheat oven to 350 degrees. Prep sheet pans with parchment, lay out rings.
(Specialized equipment note: You will need twelve 3” pastry cutters to use as forms, available at local cookware shops or online)
In a stand mixer bowl, mix eggs and sugar until white and fluffy. Beat in the butter. Sift together the flour, salt and baking powder. Add into mixer bowl until just incorporated. Form into a disk, wrap in plastic and chill dough for 90 minutes.
Easy Pastry Cream (Crème Patissière)
Prepare a bowl that will accommodate some ice water and the eventual finished cooked pastry cream saucepan.
In a saucepan, whisk together the sugar, cornstarch and salt until combined. Add about half the milk and whisk until smooth. Whisk in the eggs, then the remaining milk. Heat the pan over medium high heat to a full boil. Drop heat to medium and whisk for 1 minute. Turn off heat and add the vanilla and whisk in the butter a couple lumps at a time until smooth.
Cover the pastry cream so plastic wrap touches the surface of the cream but peel it back ¼” on one of the sides to allow steam to escape and prevent a ‘skin’ from forming. Place in ice bath.
In a non-stick saucepan, combine brown sugar, butter and cinnamon. Cook over medium heat for about 5 minutes, until the sugar dissolves. Carefully add apples and stir until well-coated and softened a bit. Let cool in pan.
Finishing the dish
Remove Palets Bretons dough disk from refrigerator. Unwrap and place between two sheets of waxed paper and roll out to 1/4” thickness. Cut with rings but leave the circles inside the cutting ring, and place on sheet pan. Chill another 20-30 minutes. Bake off 15-20 minutes until golden on top. Cool on tray then remove rings.
Whisk down the chilled pastry cream to the desired consistency, place in a piping bag snip off the the tip and pipe ribbons onto the palets. Top with Caramelized Apples.