Hilary Duff's 4½-year-old son Luca has mature taste - and mom indulges them on errands and in packed lunches

Callie Collection Wines Launch Event with Hilary Duff

Hilary Duff‘s 4½-year-old son Luca Cruz has mature taste – and his mom indulges them on errands and in packed lunches!

“He’s picky, but he would crush that cheese plate!” Hilary, 29, told PEOPLE Tuesday, pointing to a meat-and-cheese-laden platter during mom’s night out. The self-professed white-wine lover was celebrating the launch of her three Callie Collection wines in New York, complete with a DIY floral-letters station.

And when she takes Luca along for errands, the working mama reveals he has a favorite destination.

“There’s this cheese shop in Beverly Hills I go to often, and he loves to go because they give him salami and prosciutto and weird cheeses, and he houses it!” she says.

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“But then all of a sudden he’ll go through a stage where he won’t want to touch spinach, so he is picky but adventurous,” Hilary explains.

And the mom of one doesn’t stop at fun mother-son outings.

“He loves olives in his lunchbox! It’s so bizarre. But then he won’t touch his turkey sandwich,” she laughs. “I’m like, ‘You are your mother’s child, you love salty things!’ But it can be frustrating, for sure.”

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Hilary shares that she and older sister Haylie – who hosts The Real Girl’s Kitchen and is mom to daughter Ryan Ava, 21 months – both grew up cooking, inheriting their mother’s “amazing” cooking skills.

She says they share kid-friendly recipes, but Luca’s “already on a different stage of when he’s eating than [Ryan] is,” since he’s the older cousin.

“We definitely are supportive of each other and there for each other if one of us needs something, but it’s funny — it’s almost like the kids kind of stepped into the role of supporting each other and teaching each other, too,” Haylie, 32, tells PEOPLE.

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As it turns out, the cousins’ cute relationship even extends into soccer practice.

Ryan just started her little soccer class and Luca takes soccer from the same guy,” Haylie says, “so yesterday the big boys – Luca and his best friend – came for the 30 minutes before the class to show the little girls how to do soccer and how to play.”

She adds, “So it’s funny that the little ones just sort of stepped into the role of showing each other the way, too, which is so sweet to watch.”