Mi abuela hace flan casi todos los domingos.

Hace is the third-person singular present tense of hacer.

• hacer = to make / to do
• hace = he/she does, he/she makes, you formal do/make

Here it means makes. The subject is mi abuela, so hace matches she.

In Spanish, hacer is very commonly used for preparing food, especially dishes, desserts, and recipes.

So hacer flan is a very natural way to say make flan.

Other possible verbs exist:

• preparar flan = prepare flan
• cocinar = cook, but it sounds more general and is less natural for some desserts

So hacer flan is probably the most everyday, idiomatic choice here.

Because in standard Spanish, a possessive adjective like mi normally goes directly before the noun, with no article.

So you say:

• mi abuela
• mi madre
• mi casa

not:

• la mi abuela

For an English speaker, this is just the normal Spanish pattern: my grandmother = mi abuela.

Yes, often it could.

Spanish often omits the subject when it is already clear from context. So if everyone already knows you are talking about your grandmother, you could say:

• Hace flan casi todos los domingos.

That is grammatical, but without context it could also mean he/she/you formal makes flan almost every Sunday.

Including Mi abuela makes the sentence clear and natural.

Because Spanish often leaves out the article with food or things being made, eaten, bought, etc., when speaking in a general way.

So:

• Hace flan = she makes flan

This sounds natural if you are just naming the dish.

If you say hace un flan, that can suggest she makes one flan or emphasize a single item. That is possible, but it is a slightly different focus.

So:

• hace flan = general, natural
• hace un flan = one flan, more specific/countable

Because casi modifies the whole frequency expression.

• casi todos los domingos = almost every Sunday

It means she does this on most Sundays, but not literally all of them.

This is the natural word order in Spanish. Putting casi somewhere else would usually sound awkward or change the emphasis.

Both are possible.

• todos los domingos = every Sunday
• cada domingo = every Sunday

In many situations they mean basically the same thing.

Todos los domingos is extremely common and very natural in everyday Spanish. It literally looks like all the Sundays, but the meaning is every Sunday.

With casi, casi todos los domingos sounds especially natural.
Casi cada domingo is less common.

This is a standard Spanish pattern for repeated time expressions:

• todos los días = every day
• todos los lunes = every Monday
• todos los domingos = every Sunday

So the structure is:

todos + los/las + plural noun

That is why you get todos los domingos, not singular domingo.

Because Spanish uses the present tense for habitual actions, just like English does.

• Mi abuela hace flan casi todos los domingos.
• My grandmother makes flan almost every Sunday.

This is sometimes called the habitual present. It describes what usually happens, not only what is happening right now.

Because in Spanish, days of the week are normally written with lower-case letters.

So:

• domingo
• lunes
• martes

This is different from English, where Sunday is capitalized.

The same is also true for months in Spanish.

A few useful points:

• h in hace is silent
• In most of Spain, c before e is pronounced like th in think
• So hace sounds roughly like AH-theh
• abuela is stressed on bue: a-BUE-la
• casi is stressed on the first syllable: CA-si
• domingos is stressed on min: do-MIN-gos

So the most important pronunciation detail for Spain Spanish is that hace has a silent h and a th sound for the c.

Yes. That is completely natural.

• hacer flan = make flan
• preparar flan = prepare flan

Both work well. Hace flan is especially common and everyday. Prepara flan may sound a little more neutral or slightly more formal, depending on context.

The given word order is the most neutral and natural:

• Mi abuela hace flan casi todos los domingos.

Spanish does allow some movement for emphasis, but not every change sounds equally natural.

For example:

• Casi todos los domingos, mi abuela hace flan.

This is also correct, but now the time expression is being emphasized.

The original order is the best default pattern for a learner.