Jenny’s back on the block.

Surprise! Bronx-born Jennifer Lopez made an unannounced visit to the New York City borough where she grew up on Sunday to open the Center for a Healthy Childhood, a joint effort between her Lopez Family Foundation and the Montefiore Health System.

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    The pop star donated $250,000 for the project — and celebrated by appearing at Montefiore’s Community Health Fair along with her sister Lynda.

    At the fair, Lopez made a protein shake with Marco Borges, an exercise physiologist and the founder of 22 Days Nutrition — and the brains behind Beyoncé’s 22-day vegan cleanse.

    The two whipped up Lopez’s favorite drink, a spinach protein smoothie with sunflower butter. During the demonstration, the “I Luh Ya Papi” singer said her 6 1/2-year-old twins, Max and Emme, helped inspire her to serve her family a healthy breakfast.

    “I knew the stuff that I was eating wasn’t giving me energy. I realized that after a while, and I was feeding this to my kids. Is this good for them?” she said. “So I was ready to try something different. …[This smoothie] tastes fresh, and you’re doing something good for yourself. It makes a huge difference.”

    PEOPLE caught up Borges after the presentation, and he spilled the secret to creating J.Lo’s breakfast smoothie.

    Evan Agostini/Invision/AP/PEOPLE

    “It makes an unbelievably healthy [drink] full of fiber, full of omega 3, protein, and it’s a really great meal replacement or recovery drink,” he said. “She absolutely loves it. That’s her go-to drink every day.”

    Spinach Protein SmoothieMakes 1

    1 handful spinach1 frozen banana1 cup rice milk2 scoops almond or sunflower butter1 scoop protein powder

    Combine all ingredients in a blender and blend until desired consistency is achieved.

    —Michele Corriston, with reporting by Mabel MartinezThis article originally appeared on PEOPLE Great Ideas.