You can purchase individual pieces of nougat and bars at Silva Coffee's tasting bar in Warburton.
Located under the water wheel visitors centre on the main street,
1/3400 Warburton Highway, Warburton, VIC
https://www.silvacoffee.com.au/

Also available at -

Launch Fresh Fruit & Vegetables
2080 Warburton Highway, Launching Place, VIC

Cheesemonger Sophie
3/222 Maroondah Hwy, Healesville, VIC

Squitchy Lane Vineyard
8 Medhurst Road, Gruyere, VIC

Locavore
148 Main Street, Lilydale, VIC

Proserpina Bakehouse
261 Mount Dandenong Tourist Road, Ferny Creek, VIC