Lay out 3 or 4 RITZ Crackers, salted side down, on a parchment-line baking sheet. Quickly scoop 1 tablespoon gelato onto each cracker. Top each with a RITZ cracker. Press down lightly to flatten gelato to extend to cracker edges; wipe off excess and immediately place in the freezer until frozen solid, about 3 hours. Repeat with remaining crackers and gelato to make 25 sandwiches.
When the sandwiches are frozen, melt chocolate on top of a double boiler.
In small batches and working quickly, dip sandwiches halfway into melted chocolate. Immediately dip chocolate half into chopped nuts. Place sandwiches back into the freezer. Freeze 2 to 3 hours to set.
