Between the November release of his book Gmorning, Gnight! Little Pep Talks for Me & You and his return to the title role in Hamilton for the Puerto Rican premiere in January 2019, Lin-Manuel Miranda is opening Mary Poppins Returns, in theatres nationwide December 19. And, in true overachiever fashion, co-starring in a massive Disney film opposite Emily Blunt and directed by Oscar nominee Rob Marshall wasn’t enough.

“I was there to learn,” Miranda says of his time on set as lamplighter Jack. As his feature film directorial debut approaches with tick, tick… Boom!, Miranda is using every opportunity to absorb lessons from the pros, including Jon M. Chu, currently at work on the movie adaptation of Miranda’s Tony-winning In the Heights. “Rob Marshall really approaches his work like a director-choreographer. He’s so meticulous. But he also knows how to make a star’s entrance shine. Emily Blunt coming in on that kite? Come on! That’s up there with Ethel Merman coming out of the audience in Gypsy.”

In the new film, the now-grown Banks children (Ben Whishaw and Emily Mortimer) find life not working out quite as they’d envisioned it. And so the indefatigable Mary Poppins returns to their lives to add a touch of magic and to teach a new generation of Bankses how to have fun. Along for the ride with Miranda are icons of the stage and screen Dick Van Dyke (in a different role from his original Mary Poppins character Bert), Meryl Streep, Colin Firth, and Angela Lansbury.

Miranda lost no chances in indulging his inner theatre nerd with Lansbury, either. How hard did he geek out? “So hard, in fact, I played ‘The Worst Pies in London’ [from Sweeney Todd] in the makeup trailer,” he admits with a laugh. “She could not have been more lovely. You work with these legends, and all I want to do is talk about theatre with them and eight shows a week. That is such a shared experience, regardless of what generation they’re in.”

As for the coming generation who will grow up with Mary Poppins Returns in the way that previous ones did with the original, Miranda is happy to say that “we are making a joy machine. I walked to work every day with purpose and pride. We made a thing that I think is going to make a lot of people happy.”