A small bakery in France, on the Mediterranean Sea, sells choux pastry filled with "crème pâtissière" or pastry cream. They sell them with either melted chocolate or caramel icing.

Pastry Cream

    4 large egg yolks
    1/2 cup granulated sugar
    1/4 cup all-purpose flour
    2 tablespoons cornstarch
    2 cups whole milk
    1 teaspoon vanilla extract

Choux Pastry

    1/2 cup all-purpose flour
    Pinch salt
    1/2 cup water
    1/4 cup butter
    2 large eggs

Caramel Icing

    1/2 cup dark brown sugar
    1/4 cup whipping cream
    1 1/2 teaspoons butter
    1/8 teaspoon vanilla extract
    1 tablespoon whole milk
    1 1/4 cups confectioners' sugar

1.  Pastry cream: In a large bowl, whisk the egg yolks and
     sugar. Whisk in the flour and cornstarch, then milk. Strain
     into a 3-quart saucepan. Whisk constantly over medium heat.
     The mixture may bubble and it should become harder to pull
     a whisk through the custard. When thick, remove from heat
     and stir in vanilla. Pour into a small bowl, refrigerate 1 hour.

2.  Choux pastry: Preheat oven to 400 . Measure flour and salt   
     into a small bowl. Bring water and butter to a boil in a 2-quart       

     saucepan. Immediately stir in all the flour with a wooden spoon.
     Stir until dough forms a ball. Spread out into the base of a large
     bowl to cool quickly, let the dough cool 5 minutes.

3.  The easiest way to beat in one egg at a time is to use the edge
     of the wooden spoon to "cut" the eggs into the dough. The
     mixture will be slippery at first, keep stirring and cutting in
     until it becomes sticky. Stir vigorously at this point until well
     blended, repeat with second egg.

4.  Drop tablespoonfuls onto a greased baking tray. Bake in the 
     preheated oven for 10 minutes, reduce heat to 350 and bake
     an additional 25 minutes. They should be lightly browned.

5.  Set the pastries on a cooling rack, then use a scissors to cut a
     small slit in the side of each pastry to allow steam to escape.
     Pastries are best kept in a cool dry place at room temperature.   
    When ready to serve, use a piping bag to fill with custard.

6.  Caramel icing: In a 1-quart saucepan, heat brown sugar, cream
     and butter over medium heat until sugar melts. Remove from heat,
     stir in vanilla, milk and confectioners' sugar. Top filled pastries
     with warm icing. Place in the refrigerator if you are not serving the
     pastries immediately.

    Variation: Serve shells filled with ice cream and top with caramel
     or chocolate sauce. Shells may also be filled with whipped cream
     and topped with melted chocolate.