In a food processor, pulse the flour with 1/2 cup of the nuts, the salt and pepper until the nuts are finely chopped. Add the butter and process until the mixture resembles fine meal. Add the water and process until the dough comes together. Shape the dough into an 8-inch log, wrap in plastic wrap and refrigerate until firm.
Preheat the oven to 375°. Line 2 baking sheets with parchment or wax paper. Finely chop the remaining 1/4 cup of macadamia nuts and mix with the Parmesan. Cut the log into scant 1/4-inch-thick slices and arrange them on the prepared baking sheets. Brush the slices with the egg wash and sprinkle with the Parmesan mixture. Bake the crackers for about 17 minutes, or until golden brown. Let cool on the baking sheets. Transfer the crackers to a large plate and serve.
Make Ahead: The crackers can be kept in an airtight container for 3 days or frozen for up to 1 month.
Wine Recommendation: Stuckey: The 1998 Weingut Bründlmayer Grüner Veltiner Kamptal from Austria is a lively white with loads of very ripe fruit and a big hit of pepper that echoes the flavor of the crackers.Triffon: The crunchy, peppery crackers call for a rustic, palate-cleansing red such as the 1996 Selvapiana Chianti Rufina from Tuscany.