Sharing a photo of the chef from when they worked together at 4Fourteen, Fassnidge wrote that his pal would be sorely missed.
'Matt looking chuffed on the pass of 4fourteen restaurant before he lost all dockets,’ Colin wrote.
'RIP mate, you will be missed.'
Just a day before Matt’s death, Colin had spoken passionately about mental health issues in the hospitality industry, revealing that more needed to be done to nurture chefs.
Speaking to Seven’s The Daily Edition, Colin said: ‘I grew up in the Irish society of "You don't say anything, everything's okay, you're a strong man."
'And it's taken me a lot of time to just express yourself to other men, and that's what we do to our younger chefs.
'Tell them it's okay to talk and it's okay to cry.'
His comments were in response to the death of Justin Bull - who used to work for James Packer and Russell Crowe - who died last Friday. Police say his death was not suspicious.
Just a few days Justin’s wife paid tribute to her husband, saying she believed he didn’t ‘intentionally’ mean to leave her and their young son, Felix.
'I believe you didn't intentionally leave us. But that in a clouded moment you just couldn't see a clear path through,' she said.
'I will do everything I can to make sure your memory stays alive with Lixy and he achieves and experiences all the things we talked so much about. As a team and family we had so many dreams.’
If you need support, call the Lifeline 24-hour crisis support on 13 11 14