In some cookbooks or online recipes, you will be instructed to add a “knob of butter.” For instance, maybe the recipe is for a piece of grilled meat and at the end you are told to “put a knob of butter on top.” This is something you’ll get from English and Irish cooks, and for all I know, Scottish, too. “How much is a knob?” you wonder. The answer is you’re being much to exact. Cooking isn’t like baking. It is about adding enough.
A knob of butter is basically a lump of butter. If a recipe says to add a knob of butter to a pan for sautéing, it usually means to add just enough butter to cover the bottom. Since we usually use sticks of butter here in the states, that may be from one to two tablespoons. Otherwise, it will tend to mean enough to melt nicely over whatever you are adding it to. For a rule of thumb, go for around 12 to 25 grams, or one to two tablespoons of butter. BUT, you really need to judge for yourself. Do you think it needs a little more, or a little less?
In some recipes, you might even see a “large knob” or “small knob” referred to. So, really, that means, just a little butter or a generous dollop. This could be anywhere from one to four tablespoons. A “tiny knob” might be only about 1/2 teaspoon. What you need to understand is that chefs tend to add tons of butter to everything. Especially at the end of cooking. It makes things taste better, richer, and feel better in your mouth. You are not going to mess it up by adding a little too much, especially if the butter is meant to melt.
So, what if a told you to add a knob of butter to a pancake? What I mean is add enough to melt nicely over the pancake. You aren’t going to know the exact amount, but generally, you’d put on about half a tablespoon, and if you really like it rich, a whole tablespoon.
The “knob” is leftover from very early cookbooks, such as those by Fannie Merrit Farmer, where exact measurements were never given. In a cookbook from the 1800’s, you were just as likely to be told to “add a sufficient amount of butter” as opposed to any kind of exact amount. But, you might also be told, as Andrew Smith mentions in Eating History, to add “a knob of butter the size of an egg.” Likewise, “a walnut-sized knob of butter” was a frequent instruction, which is about two tablespoons, give or take.
In those early cookbooks, the amounts of ingredients were roughly estimated by sight, but there was also the assumption that the cook already had some basic knowledge. A knob of butter was about as accurate as a “blob” of butter. See also Influential and Important Early American Cookbooks
This is not to say that all early cookbooks were without accurate measurements. Amelia Simmons in American Cookery (1796) gave flour and sugar measurements by weight (suggesting perhaps people had scales). She also used measurements like “a gill,” which corresponds to about 1/2 cups (1/4 pint, or 4 fluid ounces). And, in The Virginia Housewife (1824), Mary Randolph calls for flour both in pounds and by quarts.
The word knob doesn’t only refer to a doorknob, and don’t think a knob of butter needs to be as big as a doorknob. It really can be any rounded ball, or, as in this case, lump. You might have heard of a “bed-knob.” That is the rounded ball at the top of a bedpost. Of course, we also have volume knobs, as on radio or TV’s…or at least we used to. In other words, a knob is a general word for a smallish, roundish, lump of some kind, but it is not a specific measurement. Knob is also British slang for part of a man’s anatomy. You can guess.