Line a 9x5-inch loaf pan with plastic wrap, leaving a 4-inch overhang on all sides. Place pan in freezer until ready to use.

In a small bowl, place 1 tablespoon (15 grams) cold water; sprinkle gelatin on top, and let stand until hydrated, 3 to 5 minutes.

In the bowl of a stand mixer fitted with the whisk attachment, beat cold cream at medium-high speed until soft peaks form. Transfer to a medium bowl; cover and refrigerate.

In a small heavy-bottomed saucepan, whisk together sugar, espresso, salt, and remaining ⅓ cup (80 grams) cold water. Bring to a boil over medium heat, stirring occasionally, until sugar dissolves; cook until a candy thermometer registers 240°F (116°C), about 14 minutes. Add gelatin mixture, and whisk until completely dissolved.

Clean bowl of stand mixer and whisk attachment. Using the whisk attachment, beat egg yolks at high speed until thick and pale, 3 to 4 minutes. Reduce mixer speed to medium; add sugar mixture in a slow, steady stream, and beat until pale, thick, and completely cool, about 3 minutes.

Fold one-third of whipped cream into egg yolk mixture until just combined. Gently fold in one-third of whipped cream until just combined; gently fold

in crumbled cookies, cacao nibs, and remaining whipped cream. Spoon and spread mixture evenly into prepared pan. Cover and freeze overnight.

Uncover semifreddo; invert onto a serving plate. Remove loaf pan, and discard plastic wrap. Using a small offset spatula, smooth sides, if needed. Garnish with crumbled cookies, if desired. Serve immediately.