The simplest answer is that a novella-in-flash is a short novel that’s composed of linked but individual short-short stories – each section/chapter/story is up to 1,000 words each.
Classic examples of the form include Gwendolyn Brooks’s Maud Martha (1953) Sandra Cisneros’s The House on Mango Street (1984), and Justin Torres’s We The Animals (2011). Longer works in this form are called novels-in-flash or sometimes “flash novels”.
For more information have a read of the following:
Essay at Writers Digest: What is a Novella-in-Flash and Why Should I Consider Writing One?
Essay at SmokeLong Quarterly: How to Spot a Novella-in-Flash at 100 Yards:
Meg Pokrass on writing her novella-in-flash, ‘Here, Where We Live’
Sophie Van Llewyn on writing her novella-in-flash, ‘Bottled Goods’
Interview with Michelle Elvy – BFFA Novella-in-Flash Award 2021
Retreat West Novella-in-Flash showcase October 2022 – with Gaynor Jones, Tom O’Brien, Sudha Balagopal, Debbi Voisey, David Rhymes, Hannah Sutherland and Philip Charter
Essay introducing 12 classic Novellas-in-Flash
Essay introducing 12 classic Novellas-in-Flash from the 20th century
Michael Loveday discussing the novella-in-flash for Bath Flash Fiction Award
Interview with Michael Loveday about the Novella-in-Flash at Flash Frontier
Novella-in-flash Panel Discussion for National Flash Fiction Day New Zealand (2021): – YouTube
Novella-in-Flash Craft Essay – Are We a Story or Are We Moments?
Where to publish Novellas-in-Flash and Novels-in-Flash