Tip: To make 1 cup of yogurt cheese, line a colander with a large cotton towel or double thickness of cheesecloth, and place the colander in the sink. Pour in 3 cups low-fat yogurt. After 15 minutes, transfer the colander to a bowl. Cover with plastic wrap and refrigerate for 24 hours or overnight. Gathering the edges of the towel together, gently squeeze out any remaining liquid. Transfer cheese to a separate container. Refrigerate until ready to use. Keeps 1 week.
To make crepes: Combine flour, cocoa, sugar, salt, milk, egg, 1 teaspoon oil and water in a food processor or blender and blend until smooth. Transfer to a bowl and refrigerate for 1 hour or for up to 24 hours.
To make orange syrup: Combine sugar and water in a small saucepan. Bring to a boil, add orange zest, reduce heat to low and simmer, uncovered, for 20 to 25 minutes, or until the syrup has thickened and the zest is tender. Several times during the cooking, brush the sides of the saucepan with a pastry brush dipped in cold water to keep sugar crystals from forming on the sides. Remove from heat and let cool.
To make filling: Whisk together yogurt cheese, confectioners' sugar and vanilla in a small bowl until well-blended. Cover and refrigerate.
To cook and assemble crepes: If necessary, add 1 to 2 tablespoons water to crepe batter so that it has the consistency of light cream. Heat a small nonstick skillet or crepe pan over medium heat until a drop of water sizzles when sprinkled on the surface. Reduce heat to medium-low. Brush pan with a little of the remaining 1 teaspoon oil as needed to prevent sticking. Pour about 2 tablespoons batter on the skillet and swirl to coat the bottom evenly. Cook 30 to 40 seconds until the top of the crepe has a dull surface and the edges begin to curl. Flip and cook for 20 to 30 seconds, or until the crepe is firm. Remove to a plate and cover with a dry cloth. Repeat with remaining crepes. (The crepes may be stacked until served.)
Place a crepe on a dessert plate. Spread 2 tablespoons of filling across the middle. Fold in half and spoon 1 tablespoon Chocolate Sauce over top or beside it. Spoon 2 teaspoons orange syrup and zest over the crepe. Repeat with remaining crepes.