What the phrase is doing
Grand-mère is grandmother. Put on a recipe title, as de grand-mère or à la grand-mère, it describes the dish rather than its author: the plain, home-kitchen version, as opposed to the refined or restaurant one. The one-line form is in the glossary, which owns the definitions; what follows is what the phrase is worth knowing for.
Read as English, it looks like an attribution: somebody’s actual grandmother, a family recipe passed down. It is not. It is a genre marker: a signal about the register of the recipe, in the same way that “old-fashioned” or “the way it used to be done” works in English.
And it carries a fairly specific promise. A dish labelled this way is usually the version with the shorter ingredient list, no garnish that needs a technique, and no step that requires equipment a domestic kitchen would not have. That is the useful content of the phrase.
Why the distinction is worth making
Because it changes what a reader should expect, and because the alternative reading sets up a disappointment. Someone who takes the phrase as a provenance is looking for an heirloom recipe and may conclude that a simple one is a lesser one. Someone who reads it as a category knows in advance that simplicity is the point rather than an omission.
It also belongs to a small family of French recipe-title conventions that work the same way, signalling a register rather than a source. This page names only the one it can support: the others are worth knowing about, but nothing consulted here defines them precisely enough to set out, so they are not listed.
A different French food word that is legally defined, rather than conventionally used, is boulangerie, where the term governs what a business may call itself. The contrast is instructive: French has both kinds of food vocabulary, and treating a convention as a rule or a rule as a convention both go wrong.
The other word on this title
The same title carries a second term that this site handles at length, and it is a genuine three-way ambiguity rather than a convention. Fondant names three different things in English-language recipe writing, meaning a poured icing, a rolled sugar paste and a molten chocolate cake, and which one is meant has to be read from the context every time. That is set out at fondant meaning.
Between them the two words on one recipe title illustrate the two problems this site’s glossary exists for: a phrase that means something other than it appears to, and a word that means three things at once. The full index of terms is at the glossary, and the site’s approach to quantities is at recipes.
Questions about the phrase
What does grand-mère mean on a recipe?
Literally grandmother, but on a title it is a genre marker rather than an attribution: it signals the plain, old-fashioned, home-kitchen version of a dish rather than a refined or restaurant one.
Does it mean the recipe came from someone’s grandmother?
No. It is a category, not a provenance, and closer to English "old-fashioned" or "the way it used to be done" than to a family claim.
What does it promise about the recipe?
Usually a shorter ingredient list, no garnish requiring technique, and no step needing equipment a home kitchen would not have. Simplicity is the point rather than an omission.
Is "à la grand-mère" the same as "de grand-mère"?
In this use, yes, since both mark the same register. Neither is a statement about a person.