ORONO, Maine — Vats of frosting smeared between 3,000 sandwich-sized cakes and stacked to mimic Maine’s grandest natural landmark — it’s a tribute worth about 600,000 calories.

On the whoopie pie’s first day as Maine’s official state treat, the University of Maine paid homage to the dessert by building a 4-foot-tall imitation of mile-high Mount Katahdin out of around 1,500 cream-filled cakes. Then they tore it apart and fed it to a hungry gathering of UMaine students, cooks, officials and staff at Hilltop Dining Commons on Wednesday afternoon.

“This is a great day for the state of Maine,” said Amos Orcutt, president of both the Maine Whoopie Pie Association and the University of Maine Foundation. “We now claim our rightful heritage. Take that, Pennsylvania.”

After a bill, LD 71, proposed that the whoopie pie be named the state treat, Pennsylvania objected to Maine’s attempt to claim the whoopie pie as its own, arguing that it originated there.

Orcutt said Mainers have been eating whoopie pies since the 1920s, but the earliest evidence Pennsylvanians can offer of pies in their state comes from the 1950s.

LD 71 became law on Wednesday, 90 days after it passed through the Legislature.

UMaine Dining Services makes an average of 20,000 whoopie pies each year, according to Kathy Kittridge, director of dinning operations.

It took four bakers in the university’s central bakery three days to prepare all the desserts, according to Kittridge. The crew made 2,200 pies this week alone. The 700 that didn’t go into making the mountain are distributed throughout campus markets and dinning halls to satiate sweet teeth.

A team of five spent three hours stacking whoopie pies before the event. Landslides were a persistent problem.

The idea for the event came when staff at Hilltop Commons thought a whoopie pie-themed night might be a good “monotony breaker” event for students, according to Hilltop Dining Service manager Melissa Lewis.

Originally the event was planned for next month, but another UMaine staffer pointed out that the whoopie pie would become the official state treat on Sept. 28, so the celebration was pushed forward.

“It was just something very small that turned into something exciting,” Lewis said.

During dinner Wednesday evening, students dug into the mound of mix-and-match pies — which ranged in flavor from blueberry and pumpkin to vanilla and classic chocolate.

“I’m sure it will all be gone soon,” Kittridge said. “We feed around 1,000 students per night.”