6 tablespoons pure maple syrup, plus more if desired
3 teaspoons snipped fresh chives
Process whole-wheat flour, all-purpose flour, salt, eggs, milk and oil (or butter) in a blender or food processor until smooth, scraping the sides once or twice. Transfer to a bowl, cover and refrigerate for at least 30 minutes or overnight.
Place sausage in a large nonstick skillet over medium heat. Cook, breaking it up with a wooden spoon, until no longer pink, about 5 minutes. Cover to keep warm.
Slowly whisk seltzer into the batter. Coat a large nonstick skillet with cooking spray; heat over medium-high heat. Ladle 1/3 cup batter into the center of the pan; immediately tilt and rotate the pan to spread evenly over the bottom.
Cook until the underside is lightly browned, about 30 seconds to 1 minute. Using a heatproof silicon or rubber spatula, lift the edge, then quickly grasp the crepe with your fingers and flip. Cook until the second side is lightly browned, about 20 seconds. Slide onto a plate.
Repeat with the remaining batter, spraying the pan as needed and stacking crepes as you go. If the pan begins to smoke, reduce the heat to medium. Cover crepes with a clean kitchen towel or keep warm in a 200 °F oven.
To assemble, place a crepe on a clean cutting board. Spread 1/4 cup applesauce in the center, leaving a 1- to 2-inch border. Top with 1/4 cup of the cooked sausage and 2 tablespoons cheese. Fold in the sides to make a square shape, leaving a "window" in the center. Press down on the corners, as necessary, to help keep the crepe folded. Repeat with the remaining crepes, applesauce, sausage and cheese. Drizzle each crepe with 1 tablespoon maple syrup, sprinkle with 1/2 teaspoon chives and serve immediately. Pass more syrup at the table, if desired.
Make Ahead Tip: To make ahead: Prepare the batter through Step 1 and refrigerate for up to 12 hours; refrigerate crepes between sheets of wax paper and wrapped in plastic for up to 2 days.
White whole-wheat flour, made from a special variety of white wheat, is light in color and flavor but has the same nutritional properties as regular whole-wheat flour. It is available at large supermarkets and natural-foods stores and online at bobsredmill.com or kingarthurflour.com. Store it in the freezer.