Using a food processor, process the crackers into fine crumbs.
Saute the onion and garlic with 1 Tb. water over medium-high heat for 3-5 minutes, until the aromatics soften and the water has evaporated. Add celery and saute, stirring, 3 minutes to soften. If vegetables begin to stick, deglaze with additional water as needed.
In large bowl, combine turkey meat, sauteed vegetables, onion powder, mustard, pepper, egg white, nutmeg, crumbs, and parsley. Mix well.
Form into patties and cook (turning once) in a saute pan over medium-high heat until the center temperature is 180 F. Once cooked, add desired toppings and serve.