In a letter sent to the executive board, Trian called on Cadbury to set near-term margin targets, increase long-term margin goals, add new board members, and sell off some beverage assets.
While active investors are renowned for pushing for change, Trian's blunt letter is perhaps the most aggressive strategy taken to date.
The group said that the confectionery company must affect its proposals to improve margins, "to levels closer to what most food companies achieve," as well as improve the value of its shares.
While the Cadbury share price recently declined 32p, Trian said it beleves that Cadbury's implied target value per share could be as high as 970p, almost 60 per cent above the current share price.
Cadbury has made several large organisational changes to its operations over the past year, including demerging its US beverage arm, and switching a proportion of its UK manufacturing to Poland.
Trian said it supported the demerger proposals, but viewed the changes as "too little improvement over too long a time."
If Cadbury continues with its plans, confectionery margins in 2011 would remain hundreds of basis points lower than what other confectionery companies, including Wrigley and Hershey, currently achieve, Trian claimed.
In response, Cadbury seemed unfazed by Peltz's aggressive threats, saying it believed it was in fact doing a good job of creating shareholder value.
Spokesperson Katie Bolton told ConfectioneryNews.com that the company was confident with its operations and will be continuing with its own development plans.
"The board is confident that the company's strategy is in the best interests of all its shareowners and is pleased with the progress management are making," Cadbury said.
"Recent trading performance has been strong, margin improvement plans are being actively executed and the beverages demerger is on track."
Peltz's Trian group has holdings in several global food companies, including Heinz and Kraft.
After Peltz purchased a three per cent in Kraft, the company both sold its Post cereals brand to Ralcorp, and recently acquired the biscuit division of Danone.
Trian last week increased its share in Cadbury from 3.5 per cent ot 4.5 per cent, although the company said at the time that Peltz was generally "supportive" of its operational plans.