Bake the sheets one at a time until the eclairs are puffed, golden brown, and feel light and hollow when picked up, 28 to 32 minutes.
Remove from the oven and while the eclairs are still hot (you may need to use a paper towel to handle them), and using a paring knife, make two ¼-inch holes in the bottom of each eclair (one near each end) by inserting the tip and turning in a circular motion.
Once both sheets have been baked and holes poked in the bottom, return both pans to the still-warm oven. Prop the door open with a wooden spoon and allow the eclairs to set in there for 30 minutes. Remove from the oven and cool completely before filling.
Fill the Eclairs: Place the chilled pastry cream in a pastry bag fitted with a ¼-inch round piping tip (Ateco #802 is perfect for this). Insert the tip of the bag into the holes you created on the bottom of the eclairs, and gently squeeze until filled (the cream will start to come back out of the hole on the bottom). Wipe off excess cream from the bottom and continue until all eclairs are filled.
Alternative Filling Method: You can also slice the eclairs in half horizontally and pipe (I love a large closed star tip for this – Ateco #853) the pastry cream onto the bottom half, and then cover with the top half of the puff. This is a pretty presentation but a bit messier to eat!
Make the Chocolate Glaze: Place the chopped chocolate, butter, corn syrup, and salt in a medium bowl. Microwave in 15-second increments, stirring after each, until completely melted and smooth. Working one at a time, hold each eclair upside down and dip the top in the glaze, then return to the tray. Repeat with all of the puffs. Allow the glaze to set at room temperature, about 20 to 30 minutes. Serve immediately.
RECIPE NOTES:
Storing- Filled eclairs are best eaten the same day they are made, but can be kept in an airtight container in the refrigerator for up to 2 days.
Freezing- For longer storage, freeze in an airtight container for up to 3 months. Transfer to the refrigerator to thaw before serving.
Making Ahead- The pastry cream can be made up to 5 days in advance. Unfilled, baked eclair shells store well in an airtight container for up to 2 days.
NUTRITION:
CALORIES: 158KCAL FAT: 10G SATURATED FAT: 6G TRANS FAT: 1G CHOLESTEROL: 78MG SODIUM: 98MG POTASSIUM: 89MG CARBOHYDRATES: 14G FIBER: 1G SUGAR: 8G PROTEIN: 3G VITAMIN A: 301% CALCIUM: 43% IRON: 1%