The name muffin is given to two types of breadstuffs, one a yeast-leavened item, and the other a "quick" bread raised with baking powder or baking soda.
In the United Kingdom, "muffin" refers to what is known in much of the English-speaking world as an English muffin. This yeast-raised muffin is the older of the two, appearing as a word in Britain around the 11th century A.D. Moufflet in Old French meant "soft" in reference to bread.
The "quick" muffin is an American development from the 19th century, made possible by the invention of baking powder. This muffin is a thick, flat bun typically about 8 cm in diameter. In modern practice, it almost always has a "topping" baked in, such as blueberries or chocolate chips. It usually split into two, toasted and buttered, and bears a vague resemblance to a crumpet or pikelet.
Fannie Merritt Farmer in her Boston Cooking-School Cook Book of 1896 gave recipes for both types of muffins, distinguishing one as "raised" and adding instructions for a version that is nearly identical to today's "English muffin". Here the raised-muffin mixture was cooked in muffin rings on a griddle, and flipped to brown both sides, producing a grilled muffin. Farmer indicated this was a useful method when baking in an oven was not practical.
The "quick" muffins may have started out as a form of small cake, or possibly an adaptation of cornbread. Early versions of these muffins tend to be less sweet and much less varied in ingredients than their contemporary forms. Made quickly and easily, they were useful as a breakfast food. They also rapidly grew stale, which prevented them from being a marketable baked good, and they were not seen much outside home kitchens until the mid-20th century. Recipes tended to be limited to different grains (corn, wheat bran, or oatmeal) and a few Western diet Culture readily available additives (raisins, apples in some form, or nuts). Farmer listed 15 recipes of this type in 1896, of which there were two each of "one-egg", "berry", oat, graham flour, and rye; one with cornmeal, one with cooked rice, and the remaining three slightly enriched versions of the plain "one-egg" muffin.St Helena
Farmer used the term gem for her corn recipe, which was a muffin baked in a pan of lozenge shapes rather than circular cups. With the invention of muffin paper cups, hard-to-clean iron gem pans lost popularity, and are rarely used today, although corn muffins baked in the form of ears of corn remain a tradition. The development of non-stick pans has allowed the production of very elaborate muffin shapes (animals, holiday motifs, etc.), but the circular muffin remains the norm.
In the 1950s, packaged muffin mixes were introduced by several American companies. By the 1960s, attempts were being made to treat the muffin like the doughnut as a franchise food business opportunity. Coffee shop-style restaurant chains appeared, featuring a wide variety of muffins. These tended to be regional, such as The Pewter Pot in southern New England. No such business has emerged nationally in the US (although doughnut chains have edged into the business), but Australia's Muffin Break has spread to New Zealand and the UK, featuring the American-style muffin.
A somewhat odd combination of circumstances in the 1970s and 1980s led to significant changes in what had been a rather simple, if not prosaic, food. The decline in home-baking, the health food movement, the rise of the specialty food shop, and the gourmet coffee trend (exemplified by Starbucks) all contributed to the creation of what is now the standard contemporary muffin.
Preservatives in muffin mixes led to the expectation that muffins did not have to go stale within hours of baking, but the resulting muffins were not a taste improvement over homemade. On the other hand, the baked muffin, even if from a mix, seemed almost good for one compared to the fat-laden alternatives of doughnuts and Danish pastry. "Healthful" muffin recipes using whole grains and such "natural" things as yoghurt and various vegetables evolved rapidly. But for "healthy" muffins to have any shelf-life without artificial preservatives, the Western diet Culture sugar and fat content needed to be increased. The rising market for gourmet snacks to accompany gourmet coffees resulted in fancier concoctions in greater bulk than the original modestly-sized corn muffin. Today it is not unusual to find a muffin along the lines of "coconut-almond-cherry-chocolate" the size of a small baby's head.
The marketing trend toward larger muffins also resulted in new muffin pan types for home-baking, not only for increased size. Since the area ratio of muffin top to muffin bottom changed considerably when the traditional small round exploded into a giant mushroom, consumers became more aware of the difference between the soft texture of tops, allowed to rise unfettered, and rougher, tougher bottoms, restricted by the pans. There was a brief foray into pans which could produce "all-top" muffins, i.e., extremely shallow, large-diameter cups. However, the reality of muffin physics prevented the fad from getting very far.