What Kellogg's product was introduced to compete with Post's unsuccessful "Country Squares"?

"Pop-Tarts" is a brand of rectangular, pre-baked, convenience food toaster pastries that the Kellogg Company introduced in 1964. Pop-Tarts have a sugary filling sealed inside two layers of rectangular, thin pastry crust. Most varieties are also frosted. Although sold pre-cooked, they are designed to be warmed inside a toaster or microwave oven. They are usually sold in pairs inside Mylar (previously foil) packages and do not require refrigeration.

In the 1960s, Post adapted its process for enclosing food in foil to keep it fresh without spoiling—first used for dog food—to its new toaster-prepared breakfast food. Intended to complement its cold cereals, Post announced its new product to the press in 1963 before they went to market. Post called them "Country Squares".

Because Post had revealed "Country Squares" before they were ready to be put in the marketplace, Post's biggest competitor, Kellogg, was able to develop its own version in six months. The product, advertised by an animated, anthropomorphic toaster named Milton, became so popular that Kellogg could not keep up with demand.