For the tiramisu, stir the cold coffee and all ingredients until the powdered sugar has completely dissolved.
Pour into a 0.5 L iSi device. Screw on an iSi cream capsule and shake vigorously. Chill in the refrigerator for 1-2 hours.
For the pumpkin seed brittle, caramelize granulated sugar in a pan over low heat. Add the pumpkin seeds and stir for about 1 minute.
Spread on baking paper and let cool. Serve the pumpkin seed oil cream in layers with chocolate cookies dipped in coffee in a glass.
Serve with the pumpkin seed brittle.