Traditionally, cheese blintzes are filled with farmer's cheese.  Because this is difficult to find, modern recipes use cottage cheese instead.  This makes a very runny filling, however, even if small curd cottage cheese is used.  So if you can find farmer's cheese, do try the following recipe, which is much better.  I made it up myself, so feel free to vary the proportions of the cheeses to suit your taste.

Proceed according to directions for blintz wrappers.  This will make 18-19 wrappers, just the right amount for the following filling.
 
 

Crumble farmer's cheese into a medium mixing bowl.  Soften cream cheese in microwave (or have at room temp).  Mix all ingredients and divide filling among blintz wrappers.  Then fill as directed for regular cheese blintzes.

This will make 18-19 blintzes, enough for 5-6 servings.