In a large bowl, mix the Parmesan cheese, sunflower seeds, pumpkin seeds, sesame seeds, ground and whole flaxseeds, salt, dried rosemary, garlic powder, onion powder, and Italian seasoning.
Pour in 2 1/4 cups water and stir until all ingredients are well combined.
Allow the mixture to sit for about 20 minutes (or up to 1 hour) so it thickens into a gel-like consistency.
Preheat the oven to 300°F. Line a baking sheet with parchment paper and spread the mixture in a thin, even layer (about 1/4-inch thick).
Bake for 55-60 minutes or until the crackers are firm and golden. Let cool completely before breaking into pieces.