Saturday in Prospect Park saw clusters of families and friends spread out on the early green lawns, many with boxes of homemade sweets. With outdoor gatherings on the rise as the city moves into warmer days, the question of what desserts travel well is coming up more often at neighborhood bakeries and local markets.

Brownie cookies, peanut butter blackberry bars, and pistachio halvah Rice Krispies treats have been spotted in picnic baskets from Central Park to Astoria Park this weekend. Vendors at the Union Square Greenmarket said late last week that customers are asking for confections that can withstand several hours in sun and humidity.

“People want something that won’t melt or crumble,” said Angela Ruiz, who manages a bakery stall on Flatbush Avenue. She noted a spike in requests for bar cookies and dense, chewy options. Pre-cut squares and individually wrapped pieces are popular for their portability.

A few Upper West Side delis have begun offering small packs of nut-studded cookies and cereal bars near checkout, aimed at weekend parkgoers. At Riverside Park on Sunday morning, several cyclists were seen sharing containers of homemade bars and thick cookies during a break.

As outdoor festivals and school picnics continue through June, city bakers and home cooks are likely to keep looking for desserts that hold up under spring sun. For now, dense cookies and bars remain a reliable choice for the season’s gatherings.