A team of researchers carried out a study which found the optimum thickness is 14mm and the ideal amount of butter is 0.44 grams per square inch.
The recommended cooking time gives the slice a 'golden-brown' colour and the 'ultimate balance of external crunch and internal softness'.
It has the look of 'builder's tea' and, crucially, the outside is 12 times crunchier than the middle.
The result is achieved by setting the toaster dial to 'five out of six' on a typical 900-watt appliance to produce a temperature of 154 degrees Celsius, the study revealed.
Bread expert Dr Dom Lane, a consultant food researcher, spent one week toasting and tasting a staggering 2,000 slices for his research, in his bid to assist the nation's toast eaters.
We chomp our way through more than 94.2 million slices daily, though our enjoyment can be spoiled by burnt or soggy specimens. Read More