Besim discussed his plans in online chats with a teenager in the United Kingdom during March last year.
The UK boy's overseas arrest led to Australian authorities swooping on Besim - just one week before his planned deadly attack.
Croucher said the pair conversed about the "evil" plan "as if talking about something as ordinary as football tactics".
Besim chose Anzac Day to "make sure the dogs remember this as well as their fallen heroes".
He said he was "ready to fight these dogs" on their doorstep.
"I'd love to take out some cops," Besim wrote to the UK teen.
"I was gonna meet with them then take some heads ahaha."
Besim had penned a suicide note, though some of the online conversations revealed "faint" suggestions he might have backed out.
He pleaded guilty to one count of conspiring to do an act in preparation for or planning a terror act - a charge that carries a maximum sentence of life imprisonment.
The court heard Besim was radicalised by older, influential extremists he met at the now defunct Al-Furqan Islamic Centre, including senior Islamic State recruiter Neil Prakash.
He was also greatly affected by the 2014 death of his friend Numan Haider and became alienated from society.
Haider, 18, was shot dead outside Endeavour Hills police station after stabbing two counter-terrorism officers.
Besim was with him in the hours before the attack.
Prison staff last year found a hand-drawn Isis (Islamic State) flag in Besim's cell as well as newspaper clippings about violent jihadis fighting overseas.
The teen has been engaging with moderate imams from the Islamic Council of Victoria and claims he has changed his radical views through reflections and reading over a number of months.
But Croucher wasn't satisfied "on the balance of probabilities" that Besim had renounced violent jihadism.
He also said the teen's guilty plea, lack of prior convictions, apparent contrition and youth suggested he had good prospects for rehabilitation.
At Besim's plea hearing last month in the Victorian Supreme Court, his lawyer, George Georgiou, SC, said Besim was never considered a "problem child" by his parents.
"They regarded him as a kind and considerate young person who showed respect towards his elders," he said. "He did not smoke, did not drink, did not indulge in drugs."
He said Besim wasn't being kept with the mainstream prison population because of the nature of his charge.
"There is a fair chance he will remain in protection for a significant part of his sentence," Georgiou said.
Besim has been in custody since April 18 last year when 200 heavily armed officers swooped on the city's southeast, arresting five teens and seizing knives and swords.
Besim was handed a 10-year jail sentence and must serve at least seven and a half before he is eligible for parole.
He blew kisses to a large group of supporters as he was led away.
Teen's terror plot
• Sevdet Ramadan Besim introduced to the Al-Furqan Islamic Centre in Springvale and Isis (Islamic State) recruiter Neil Prakash while in high school.
• Late 2013: Besim meets 18-year-old Numan Haider at a Hallam mosque.
• September 22, 2014: Isis issues a fatwa calling on supporters to target police, soldiers and kill unbelievers.
• September 23, 2014: Haider shot dead at Endeavour Hills police station after stabbing two counter-terrorism police officers.
• Affected by Haider's death, Besim decides to travel to Middle East and join Isis.
• His passport application is rejected.
• February 2015: Melbourne Anzac Day parades and the Shrine of Remembrance researched.
• March 2015: Besim chats with a UK teen about his Anzac Day plan to run over and behead a police officer, saying: "I feel like a young kid with a ticket to disney world cant wait ahahah."
• They also talk about packing a kangaroo with explosives, painting on a Isis symbol and setting it on police.
• Late March 2015: UK teen arrested.
• April 18, 2015: Besim arrested in counter-terror raids, Rambo knife found in his car.
• June 2016: Besim pleads guilty to a terror-related charge.
• September 5, 2016: Besim, 19, sentenced to 10 years jail, with a minimum of at least 7.5 years.
- AAP
