Prepare the patisserie cream:
Mix the egg yolks and sugar together.
Add the cornstarch and dissolve completely.
Heat the milk to a boil.
Pour the boiled milk over the egg yolk mixture and whisk vigorously to avoid lumps.
Return this mixture to the saucepan and bring to a boil again. Add the food coloring. Set aside off the heat.
Prepare the confit zests:
In a small saucepan, pour in the sugar, water, and lemon peels.
Over low heat, let the peels confit until they are translucent. Drain. Set aside.
Open the eclairs in half lengthwise.
Fill a piping bag with the pink patisserie cream.
Arrange the cranberries and confit zests.