Beat together eggs, water, milk, salt and flour with electric beaters. Place in the fridge to stand for about 30 minutes.
Heat a small bit of butter in a small frying pan over medium high. pour in about 1/4 cup of mixture, tilting frypan to spread the mixture. Flip it before it browns, then fry the other side for a few seconds. Turn out on to a tea-towel and repeat until all butter and mixture is used. Set aside.
Combine ricotta and cottage cheese. Stir in egg yolk, vanilla, zest and 1/3 cup sugar. Fold into the wrapper then fry in knob of butter until golden brown.
Mix together 3 cups of blueberries, sugar and cornflour in a saucepan. Bring to a boil then stir until it thickens, about 3 minutes. Stir in additional cup of blueberries. Serve over the warm blintzes.