Described as a ‘Glaswegian twist’ on the Italian food it is served with grated almonds on top of the pizza dough, caramel sauce and a scoop of chocolate ice cream.
It is packed with Mars
Bar chunks then cooked in batter and dubbed by its owners as the "Mars-gherita Pizza".
With an estimated 1,973 calories packed into the snack, sold at Roman’s Pizzeria in Merchant City, locals have been flocking to try it.
Roman’s general manager, Fraser Walker, said the idea behind the deep fried Mars Bar calzone came from a simple conversation with the head chef.
The 36-year-old, from Kelvindale, Glasgow, said: "Well the shop has been open here for about five and a half months and we wanted to bring out something different.
"This is because we are known for our Roman-style pizza, and after speaking to the chef about different ideas we came up with that.
"We've seen restaurants adding Nutella in a calzone so we just thought the deep fried mars bar is a Scottish thing. So why not put it in a calzone?
"It's definitely not a dessert for someone who is on a diet.
"I would say people should share it because it's very sweet unless you have a sweet tooth or are really hungry."
Costing £4.50, the calzone has been a hit with punters, with one person even asking a relative to send a pizza to Germany.
Head chef, Dawid Radzinski, said: "I've been a chef for 20 years and what we've done is completely original.
"When I first made it, we all tried it together and we all loved it. The dessert has been here since Monday and people think it's really tasty.
"I think this was a great idea"
12" pizza dough = 120 calories
Two deep fried mars bars = 1,200 calories
Caramel sauce 100g = 300 calories
One tablespoon (12.6g) of sugar = 48 calories
A handful of almonds = 162 calories
One scoop of chocolate ice cream = 143 calories
Total = 1,973 calories