For the violet or rose flavored Êclairs, whisk the egg yolks well with 40 g sugar and salt. Gradually mix in the flour and cornstarch. In a saucepan, bring the milk to a rapid boil with 40 g of sugar. Remove the saucepan from the heat, pour a ladleful of milk over the egg yolk mixture and whisk vigorously to combine. Add this mixture to the milk in the saucepan and whisk until smooth. Bring cream to a boil while stirring, then remove saucepan from heat (if cream thickens too much, simmer for 1-2 minutes while stirring constantly, this will make cream more liquid again). Pour cream into a bowl and immediately cover with plastic wrap to prevent a skin from forming. Place the cream in the refrigerator until lukewarm. Whisk the violet flavoring into the cold cream until smooth and airy.
For rose cream, place measuring cup and whisk in refrigerator before preparing. Whip cream with the whisks of a hand mixer first on medium speed, then on high speed until stiff. Add powdered sugar,vanilla pulp, rose water and a little red food coloring to give the cream a pale pink color and continue beating until the cream sticks to the whisks. Preheat the oven to 150°C.
For the éclairs, pour the milk and water into a saucepan and add the cubed butter, salt and sugar. Stir over high heat with a wooden spoon until the butter has set.