The grandson of the inventor of Reese's peanut butter cups took a sledgehammer to the Hershey's Company, blasting it for replacing his grandfather's original recipe with lower quality ingredients.

In an open letter to Hershey's posted to Linkedin on Sunday, Brad Reese said Hershey's has been "quietly replacing" his grandfather HB Reese's original recipe, comprised of milk chocolate and peanut butter, eroding trust with consumers.

"My grandfather, H. B. REESE (Who Invented REESE'S), built REESE'S on a simple, enduring architecture: Milk Chocolate + Peanut Butter. Not a flavor idea. Not a marketing construct. A real, tangible product identity that consumers have trusted for a century," Brad wrote.

"But today, REESE'S identity is being rewritten, not by storytellers, but by formulation decisions that replace Milk Chocolate with compound coatings and Peanut Butter with peanut?butter?style crèmes across multiple REESE'S products."

Speaking to Fox Business, Brad recalled recently purchasing a bag of Reese's hearts and throwing the bag away, saying, "It was not edible." 

"I went and bought a bag, and I took a couple bites, and I had to throw the bag in the garbage," Reese said. "I couldn't eat it. It was not edible, and I looked at the packaging … and there was no milk chocolate, there was no peanut butter — it was all vegetable oils and fats."

"You have to understand. I used to eat a Reese's product every day. This is very devastating for me," Brad added in comments to the Associated Press.

Brad argued that in popular Reese's spin-offs like Take 5 and Fast Break, milk chocolate has been replaced with "milk chocolate-flavored coating and peanut butter crème," reflected on the products' packaging.

The subtle change is noticeable in various Hershey's products. For instance, Mr. Goodbar used to list "milk chocolate" as its main ingredient; however, it now states "chocolate candy."

Additionally, "In the early 2000's, when Hershey released White Reese's, they were made with white chocolate. Now they're made with a white creme," Brad told the AP.

In a statement addressing Reese's concerns, Hershey claimed Reese's Peanut Butter Cups are still "made the same way they always have been; starting with roasting fresh peanuts to make our unique, one-of-a-kind peanut butter that is then combined with milk chocolate."

They added, however, the company has made some "product recipe adjustments" to be able to make various spin-off products.

"We make product recipe adjustments that allow us to make new shapes, sizes and innovations that Reese's fans have come to love and ask for, while always protecting the essence of what makes Reese's unique and special: the perfect combination of chocolate and peanut butter," the company said.