Put the water with the oil to boil on the stove and add the flour all at once, stirring vigorously until smooth. Leave it to cool and add the eggs one by one, beating with a mixer until they become a smooth, sticky mixture.
Using a pastry bag or spoon, take from the mixture and put it in an oven dish, covered with a sheet of baking paper, keeping a little space between each.
Bake in a preheated 392°F (200 °C) oven for about 30 minutes. To make the cream, boil the milk and sugar, pour the flour diluted with water in a thin trickle into them and stir to thicken.
Remove it from the heat and allow it to cool, then add the butter and vanilla and mix. The cream needs to cool completely, then, add the other cream to it and mix gently to keep it fluffy.
Cut the eclairs down the middle and fill them with the cream. Glaze the top with a little melted chocolate, mixed with a little liquid cream.