“Hamilton” phenom Lin-Manuel Miranda is poised to possibly become the youngest EGOT (Emmy, Grammy, Oscar and Tony winner) in history at this Sunday’s Oscars, but that might not even be the most significant to happen that night -- he’s fulfilling a promise he made 27 years ago to his mom.

Lin, who is nominated for Best Original Song for How Far I’ll Go from “Moana” recalled, “I remember as a kid my mom saying, ‘When you get nominated for an Oscar, I’m your date.’ It’s such a pie-in-the-sky thing to say, but she always believed. I think she believed even before I did. So I’m thrilled to get to keep that promise.”

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Lin’s mom, Dr. Luz Towns-Miranda, replied, “Going to the Academy Awards is going to be somewhat surreal, because I always imagined my son on the red carpet, but I didn’t quite see myself there, even though for years I’ve been talking about [going.]”

Going to the Oscars requires a special kind of dress (to say the least!), so Luz asked style maven Stacy London to help her find just the right one. You might remember that Stacy helped Dr. Luz organize her massive wardrobe last year, and the two are pals now. (Luz told us, “I’m teaching her how to knit. She needs to practice more.”)

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Stacy took Luz shopping at Amarium (a luxury fashion rental website and app) to find the THE dress, and the one they landed on was nothing short of perfect. Stacy described the simple and elegant black-and-white number, “It’s sleek, it’s subtle and we see her before we see the dress rather than seeing the dress before her.”

When Lin saw his mom in her dress for the first time, his reaction was, “The only awkward part will be when people come up and say ‘Congrats on your nomination for ‘Jackie.’

“I feel like Jackie O. and [Audrey] Hepburn rolled into one,” Luz said.

WATCH: Stacy London on Planning Outfits for the Week: Think of It as Meal Prep

Watch above to see Lin’s ecstatic and emotional reaction to seeing his mom red-carpet-ready, and check out the video below to hear Lin-Manuel and Luz reminisce about the long road to the Oscars.