Prepare the pastry cream as per the instructions in the pastry cream post linked in the notes section below. The quantity in this recipe is smaller than that one, so make sure you choose these quantities (unless you'd like some leftover pastry cream). Pop it in the fridge to chill and firm up completely - I like to make it the night before.
Preheat the oven to 200C/400F. Very lightly grease and then line a large baking tray. Greasing the tray first will ensure the paper doesn't slip around as you pipe your eclairs.
Prepare the choux pastry dough as per the instructions in the gluten free choux pastry recipe linked below. Prepare the dough up until step 7.
Place the choux pastry in a piping bag with a large round nozzle. Pipe 8-10 eclairs that are roughly 10cm X 3cm rectangles (4 inch X 1 inch). I like to pipe them a few layers upwards to give them a little bit of height. Hopefully the dough is holding shape as you pipe onto the tray. If not, you may have added a bit much egg (but bake them anyway because sometimes choux pastry can surprise you!).
Bake for 15-20 minutes or until the eclairs are golden and puffed. If they are extra golden, you might like to place a piece of foil on the top oven rack to prevent them from over-browning.
Turn the oven down to 150C/300F. Bake the eclairs for a further 10-20 minutes to bake them through thoroughly.
Remove the eclairs from the oven. Working quickly, poke 1-2 small air holes in each eclair (I like to do one on each short end of the eclair) using a skewer. This will help any air escape and should hopefully mean your eclairs hold their shape. Allow the eclairs to cool completely on the tray.
Using a shape knife, cut two small circular holes in the bottom of each eclair. You will use these holes to pipe the pastry cream into the eclair. Alternatively, you can slice each eclair in half longways and sandwich the pastry cream between the top and bottom slice.
Pipe pastry cream into each eclair until it puffs up a little (if you are filling the eclairs through the holes in the bottom) or until it looks nicely filled (if you are sandwiching the pastry cream in).
Repeat until you have filled all the eclairs.
To make the chocolate topping, place the chocolate and oil or butter in a small heatproof bowl over a small pot 1/3 filled with water. Ensure the water doesn't touch the base of the bowl. Turn the heat to medium and cook, stirring regularly, until the chocolate has fully melted.
Dip the top of each eclair in the melted chocolate. Allow the excess chocolate to drip off thoroughly while the eclair is inverted, then place it on a cooling rack to allow the chocolate to set.
These eclairs are best consumed on the day of making, but can keep in the fridge in an airtight container for a couple of days.