Make the Vanilla Pastry Cream:  Whisk egg yolks, cornstarch, half and half or milk, sugar and salt together in a medium saucepan.  Add butter.  Place pan over medium low heat and whisk constantly until butter melts and mixture becomes smooth and thick, about 3-5 minutes.  Strain mixture through a fine mesh strainer into a clean bowl.  Stir in vanilla. Place a piece of parchment paper directly on top of the pastry cream, followed by a layer of plastic wrap (this prevents the custard from forming a skin).  Refrigerate until you are ready to use.  (Vanilla Pastry Cream can be made 1-2 days in advance.)

Make the Pancakes:  Combine all ingredients in a blender and blend until completely smooth.  Transfer to the refrigerator to rest for at least 2 hours or up to 2 days.

Heat a 10 inch nonstick skillet over medium heat.  Stir the batter briefly to recombine.  Brush skillet with melted butter.  Pick the skillet up off of the burner and quickly add a ¼ cup of batter.  Immediately begin swirling the batter around the skillet so that it coats the bottom of the pan.  Return the skillet to the burner.  Cook until the pancake is golden brown in spots on the bottom, about 1 minute.  Use a spatula to loosen the pancake, flip it over and continue to cook on the other side for about 1 minute.  Remove from the skillet and transfer to a plate to cool.  Continue with the remaining batter.

Assemble the Pancakes:  When you are ready to serve, heat the Blueberry Cardamom Compote until warmed through.  Transfer a pancake to a clean work surface.  Spread a layer of vanilla pastry cream on the top and fold into quarters.  Top with Blueberry Cardamom Compote.  Top with whipped cream and/or sprinkle with powdered sugar.  Repeat with remaining pancakes.  Serve.