Combine the flour, eggs, milk, water, vanilla, sugar, salt, and melted butter in a blender. Blend or whisk until the batter is smooth and well combined.
Strain the mixture (important) and let it rest for 10 minutes.
Place a non-stick skillet or crepe pan over medium heat. Use a brush or a paper towel to spread the melted butter.
Pour about 1/4 cup of the crepe batter into the hot pan and swirl it around to coat the bottom evenly. Cook for about 1-2 minutes, until the edges of the crepe are set, and the bottom is lightly golden.
Flip the crepe and cook for an additional 30 seconds to 1 minute on the other side. Transfer the cooked crepe to a plate and repeat with the remaining batter, stacking the crepes on top of each other as you cook them.
Combine the filling ingredients in a medium mixing bowl (start with 2 tablespoons of sugar). Stir until the filling is smooth and well combined.
Taste and add sugar if needed.
Place a spoonful of the cheese filling in the center of each crepe. Fold the sides of the crepe over the filling, then fold the top and bottom to form a rectangular shape, similar to an envelope. Next, roll the blintz up and over the filling like a burrito, tucking the edges in as you roll.