But that's not all. Last summer, the scrum-half was voted Player of the Match at the World Rugby U20 Championship against hosts South Africa, in another day that the Azzurrini will find hard to forget.
"The satisfaction is equal: we made history in both cases," says the number nine who plays in Vicenza, but is part of the under-23 academy in Treviso. "Perhaps the one with South Africa was a bit more special, given the weather conditions. In both cases we won away from home and, in France, in an atmosphere we are not at all used to - a stadium full of fans cheering from the first to the last minute."
A student in economics and sports management, Casilio has been a member of the Marca academy for a couple of years, and last season went on loan with Treviso-based Rugby Paese. In their green-and-white colours can also be found his brother Nicolò, a fellow scrum-half, who arrived from Zebre Parma following stints with Calvisano and Colorno.
"He gives me a lot of advice. We see each other and compare notes every day, because I've decided to live in Treviso anyway. I do all the first part of the week and the bulk of the work with Benetton and then for the final part I go to Vicenza. Also in this period I'll train with the green-and-whites first team, during breaks in the Six Nations U20 tournament. For now, however, I'm happy in Treviso and I don't know what my future holds."
Casilio, who has played rugby since the age of five, has gained maturity after broadening his horizons with the Wasps Academy and at Oxford City College, where he was studying.
His nickname is 'Spadino' (a type of small sword), bestowed upon him by former Azzurri stalwart Fabio Ongaro, now Benetton's scrum coach. That Friday night he lived up to the moniker, an arcing effort seeing him touch down right in the corner and drawing first blood against the French.
"It was the only space I saw open. The ball had come out of the scrum and I just thought about picking it up - that was the first thing that went through my head, as well as aiming for where there was a gap. It was a game played point to point, handled well, despite the tension, and even when we picked up a yellow card in the second half and they came forward, we were good at keeping in touch with them. I think we were aware from the start that we could win. We were coming from a good test and a game we had lost with a lot of regret against Ireland. In the dressing room we told ourselves that we had to build on the last play in Cork and try to make up for it."
And in the 80th minute, France lost their ball at the lineout. Cue an irrepressible scream of joy from the Italian party.
"We are still very small compared to other nations, so to beat France on their turf was really something extraordinary. The celebrations went on all evening, because then everyone went back to their home club. We had already coming in on the back of an arduous journey of planes and trains, but it was definitely worth it. The atmosphere was one of pure joy. The coaches were happy. The only disappointment was that we didn't have some music because we had forgotten the speaker."
Davide Ascari was there, though. "Yes," he laughs. "He provided the soundtrack to the tune of Turandot."
Now it's back home, with the hope that Stadio Comunale di Monigo will be in the same mood as the Stade Raoul Barrière when they host Scotland, followed by the finale in Wales. On paper, two games within their grasp.
"On paper only. In the meantime, I hope the Treviso stadium is sold out. I went to check the ticket office and it seems to me that it is already more than half full. I think this team deserves a warm cheer like the ones our opponents receive when we play away.
"As for the games, we must not underestimate anything from the opening whistle. We must continue to have the right mentality, which in the first home match against England we lacked a bit; we did not have the right approach and that led us to suffer in certain situations, which was not the real Italy. And then we have to think that we haven't reached our goal yet."
Which is?
'We want to at least match what we did last year, or claim the satisfaction of getting three wins."
