Line a baking sheet with foil or parchment paper; set aside.
Place water in a 2-quart saucepan. Pour sugar in a thin stream in the center of the pan to form a low mound. Don't stir; use your fingers to pat sugar mound down until it is entirely moistened. Any sugar touching edges of pan should be below the water line. Cover and cook over medium heat for a few minutes without stirring until sugar is dissolved and syrup looks clear.
Uncover and continue to cook without stirring until syrup begins to color slightly. Swirl pan gently (rather than stirring) if syrup is coloring unevenly. Use a skewer to drop a bead of syrup on a plate from time to time. When a a drop looks pale amber, add the nuts. using a silicone spatula gently turn nuts until they are completely coated with syrup.
Continue to cook, gently pushing nuts around if syrup is coloring unevenly, until a drop of syrup looks golden amber on the plate (about 30 minutes total). If syrup gets too dark, it will taste bitter. Immediately scrape mixture onto lined baking sheet and spread it out as well as you can.
While still warm but cool enough to handle, break into pieces. Transfer to resealable plastic bag. Keep airtight until needed, so they will not become sticky.
When ready to use, break caramel into smaller pieces; chop medium fine or pulse in food processor. In a large chilled bowl, beat cream until it holds soft peaks. Fold in chopped caramel. Makes 3 cups.