The Andretti Autosport driver took a lights-to-flag victory having never been headed from pole during the 24-lap contest, but only after resisting intense early pressure from Nissan’s Norman Nato and Jaguar’s Sam Bird who completed the podium.
Bird’s team-mate Evans was forced to retire after colliding with fellow Kiwi and championship leader Cassidy at Turn 7 on the second lap as the pair ran in tandem behind Dennis.
The Jaguar driver locked the rear-axle under braking and ran into the back of Cassidy, which launched Evans into the air and then the barrier as Cassidy took to the escape road.
The safety car was deployed to remove debris, with both Evans and Cassidy rejoining at the back of the field.
After stopping for a new front wing Evans, who had taken victory in Saturday’s opening Rome E-Prix, rejoined for two more laps before retiring in the pits.
Envision Racing’s Cassidy, who entered the race two points ahead of Dennis in the standings, never recovered and finished 14th after contact with Andretti’s Andre Lotterer on the final lap at T14 which is under investigation.
Once the safety car had headed to the pits following the Evans and Cassidy crash, Dennis led from Nato, Bird and Dan Ticktum, with Nato making small contact on the back of the Andretti machine three laps later into Turn 17 which damaged his front wing.
The damage meant Nato struggled to match the pace of Dennis for the remainder of the race, which proved critical in the closing laps.
Bird moved ahead shortly after Nato suffered the damage and pressured Dennis hard over the following laps, with his strongest effort coming on lap 12 into the 90-degree left of Turn 7.
Unable to find a way past, Bird dropped back behind Nato after activating his final Attack Mode on lap 18.
Although with significantly more energy over the final laps, Bird was unable to find a way past Nato as the pair finished three seconds behind Dennis.
The Maseratis of Edoardo Mortara and Maximilian Guenther claimed fourth and sixth respectively having shadowed the leaders throughout, as Envision’s Sebastien Buemi finished between them.
Porsche’s Pascal Wehrlein took seventh having started down in 15th, as Stoffel Vandoorne (DS Penske), Dan Ticktum (NIO 333) and Nico Muller (Abt Cupra) completed the top 10.
