If using fresh asparagus, snap off and discard woody bases from asparagus. If desired, scrape off scales from asparagus spears. Cook asparagus, covered, in a small amount of boiling water about 10 minutes or until soft and tender; drain. If using frozen asparagus, cook according to package directions using maximum time given; drain. Carefully spread asparagus on a double layer of paper towels; drain well. Pat dry with paper towel.

Transfer asparagus to a medium bowl. Using a fork, mash the asparagus. Drain out all the excess water using a sieve (excess water will make the sandwiches soggy). Stir in mayonnaise, Parmesan cheese, salt, and white pepper; mix thoroughly to a spreadable consistency.

Spread butter on one side of each slice of white bread. Spread asparagus mixture over buttered side of each slice. Top 2 slices of white bread with a slice of wheat bread. Place the 2 remaining slices of white bread, asparagus side down, on top each slice of whole wheat.

To serve, using a sharp serrated knife, slice crusts from all four sides of each sandwich. Cut each sandwich into 4 triangles or 4 squares. Arrange on a platter with the cut edges upward. Garnish with sprigs of parsley or microgreens. Serve at once or cover and chill up to 1 hour. Makes 8 small sandwiches.