Lin-Manuel Miranda Says He's 'Surprised' by 'Encanto' 's Record-Breaking Success: 'But I'll Take It!'

"We Don't Talk About Bruno" — the breakout song from Disney's latest hit, Encanto — has smashed records, becoming the highest-charting song from a Disney animated movie in 26 years. And no one is more shocked than its composer, Lin-Manuel Miranda.

"I'm surprised it's 'Bruno,' " Miranda, 42, tells PEOPLE exclusively, of the tune's success. "I feel like this is my 'Send in the Clowns,' which was the late Stephen Sondheim's biggest hit and probably the most random of an incredible career and life making music. But I'll take it!"

Just on Wednesday, it was reported that "We Don't Talk About Bruno" surpassed Frozen's Oscar-winning hit "Let It Go" as the biggest Billboard Hot 100 hit from Disney's animated filmography.

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"[Frozen scribes] Kristen and Bobby Lopez, they are truly like artistic siblings to me," Miranda says. "I went to the same high school and elementary school as Bobby, we learned from the same music teacher. And when I'm struggling with a tune, they're the ones I call for advice because they know the pressure of writing a song for a moment in a movie that is going to be seen by millions of families. In fact, while working on Encanto, I remember specifically calling them on 'Waiting for a Miracle,' because I didn't know how to make it soar in the last section and they were incredibly helpful. So they've been so supportive."

"Still, it's crazy," Miranda adds. "This song has surprised me at every turn."

The song finds members of the magical Madrigal family singing about Bruno, their missing relative (voiced by John Leguizamo) blessed with the ability to see into the future who mysteriously disappeared one day after making a prediction about the film's heroine, Mirabel (Stephanie Beatriz).

Like "The Family Madrigal," the movie's opening number," the song features multiple members of the family's large cast of characters singing together, with Beatriz credited on the tune as well as Carolina Gaitán, Mauro Castillo, Adassa, Rhenzy Feliz, Diane Guerrero, and others.

"Our thesis for the film was, 'Can we tell a story with three generations of family and really give them complexity without them getting winnowed away in the story making process?' " Miranda explains. "Oftentimes in movies, you cut away unimportant characters, but we wanted to hold on to them. My first salvo in protecting them was writing the opening number, 'The Family Madrigal,' where I list everyone in the clearest family tree possible. And 'Bruno' was the logical next step."

Miranda uses the tune to effortlessly intertwine secrets from the Madrigals, including a hidden love triangle between cousins Dolores (Adassa) and Isabela (Guerrero).

"I pitched it as an 'End of Act One number,' " Miranda explains, the Hamilton and In the Heights composer and lyricist referencing how musicals typically have a big group number before an intermission. "I thought it could be a group gossip number, because it'd give us an opportunity to get little solos from characters who aren't going to necessarily have time to get their own song. So it comes in a long line of songs, like 'One Day More' [from Les Miserables] or 'A Weekend in the Country' [from A Little Night Music] where you introduce everyone's themes and you smash all their themes together, which is always incredibly satisfying."

The tune's eerie sound was something Miranda hoped would not only play to the "ghost story" of Bruno's absence, but also to the way the legend of his prophecies had been interpreted.

"I liked the idea that everything he predicted is super predictable," Miranda notes. "Like, of course you're going to be stressed out on your wedding day, and if your feelings control the weather, it's going to rain. That's just going to happen. Yes, goldfish die quickly! So I wanted it to be one of those things that feels spooky at the first pass, but then when you watch the movie the second time, you're like, 'Oh, that is naturally what is going to happen. And everyone is seeing these predictions in the worst light, as opposed to them actually being doom and gloom.' "

And as for that catchy "Bruno-no-no" lyric, that instantly popped into Miranda's head when he saw Bruno as a potential name for the character.

"His name was Oscar for the first year or so of development and then they were like, 'It doesn't work. There's a lot of Oscar Madrigals in Columbia and it's way too common a name.' So they gave me a list, and when he said Bruno, I just said, 'Stop. Got it,' " Miranda recalls. "I knew I could play with the 'no, no, no.' "

It didn't take long for the song to come together from there. And thought Miranda didn't see its success coming, at least one person in his family did.

"I haven't told this to anyone before, but when I was writing this it was April or May of 2020 and I was in lockdown with my in-laws, who were staying with us because they are sort of the most vulnerable population," Miranda tells PEOPLE. "And I should have known this song was good, because my father-in-law was like, 'Lin, I normally don't say anything about what you do, but I haven't been able to stop singing that Bruno thing for like a week.' And this was before anyone knew who it was., he just heard me singing that from my room when I was writing it. So that should have been the tip off way back when."

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Ultimately, Miranda says he's happy to have created something that sits up there with the beloved songs from the Disney animated catalogue.

"It's really humbling," he says. "I'm here talking to you because of the golden era of Disney musicals from 1989 through 1994, where [Little Mermaid, Beauty and the Beast, and Aladdin composers] Alan Menken and Howard Ashman just could not stop writing hit songs. And that's what made me fall in love with musicals. When I write, I'm chasing this feeling I had when I saw Sebastian the crab start singing 'Under the Sea' — this total weightlessness, probably my first real goosebumps moment in a movie theater. I'm writing to that nine year old version of me. So to not only be in their company, but to have created something that is resonating with kids now, means more than I can say."

There's just one kid who might be a little sick of it: Miranda's own 7-year-old son, Sebastian.

"My son came home from school today and he was like, 'Daddy, everyone's singing it,' " Miranda joked of his eldest, who he shares with wife Vanessa Nadal (the two are also parents to 3-year-old son Francisco). "He's both proud and like, 'All right, already.' Because remember, he heard that song last May. He's way over it."

Encanto is now streaming on Disney+.