In a medium saucepan bring water, butter, sugar, and salt to a boil. Add flour and stir with a wooden spoon for two minutes. The mixture will pull away from the sides of the pan, form a ball and leave a film on the sides and bottom on the pan.

Transfer to bowl on an electric mixer and mix on low speed for 5 minutes or until mixture has cooled. Add eggs one at a time, mixing well after each addition.

Transfer batter to a piping bag fitted with a large round tip. Pipe lines approximately 4-inches long. If you get a sharp edge, dip your finger in water and gently flatten dough.

Bake for 10 minutes, then reduce the oven to 325°F and bake for an additional 30 minutes until puffed and golden brown. Transfer to a wire rack and cool completely.

Make the pastry cream: Add milk to a medium saucepan. Remove from heat. Whisk egg, yolks, sugar, salt, and cornstarch in a large bowl. Whisk until mixture turns a lighter shade of yellow, about 1 minute. Slowly pour milk in, whisking constantly to avoid scrambling eggs.

Pour mixture back into saucepan. Cook over low heat and stir until mixture is thick and coats back of a spoon, about 5 minutes.

Stir in butter and vanilla. Strain through a sieve. Transfer to a bowl and cover with plastic wrap and chill for up to 3 days.

Make the chocolate glaze: Add chocolate chips to a medium size bowl. Heat cream in the microwave for 1 minute. Pour hot cream over chocolate. Add butter and corn syrup. Whisk until smooth.

Assemble: Fill pastry bag with pastry cream. Insert into the side of an eclair and pipe until full. Dip tops of eclairs in chocolate glaze. Repeat until all eclairs are filled and dipped in glaze.