Η μαμά μου βάζει καρύδια και αμύγδαλα στο κέικ, αλλά εγώ τα προτιμώ στο γιαούρτι.

In Greek, the definite article is used much more often than in English. With family words like μαμά, μπαμπάς, αδελφή, etc., Greek normally says:

• η μαμά μου = my mom
• ο μπαμπάς μου = my dad

So η here does not make it sound like the mom of mine in an unnatural way. It is simply the normal Greek structure.

Also, Η is capitalized only because it is at the beginning of the sentence. Normally it would be η.

Because Greek usually expresses possession with a weak pronoun placed after the noun:

• η μαμά μου = my mom
• το σπίτι μου = my house
• οι φίλοι μου = my friends

So μου literally means of me / my, but in normal Greek it follows the noun.

This is one of the most basic differences from English word order.

Βάζει is the 3rd person singular present of βάζω.

Here it means something like:

• puts
• adds

So:

• Η μαμά μου βάζει... = My mom puts/adds...

A few related forms:

• βάζω = I put
• βάζεις = you put
• βάζει = he/she/it puts

In cooking contexts, βάζω often means add.

Because Greek, like English, can leave plural objects without an article when speaking generally or introducing them as ingredients.

So:

• βάζει καρύδια και αμύγδαλα = she adds walnuts and almonds

If you used articles:

• βάζει τα καρύδια και τα αμύγδαλα

that would sound more like she adds the walnuts and the almonds, meaning specific ones already known from the context.

Without the articles, it sounds more natural for a general ingredient statement.

Στο is a contraction of:

• σε + το = στο

So:

• στο κέικ = in/into the cake
• στο γιαούρτι = in/into the yogurt

The preposition σε is very common in Greek and can mean:

• in
• into
• on
• at
• sometimes even to, depending on context

In this sentence, it marks where the nuts go or where they are preferred.

That is true: Greek often omits subject pronouns because the verb ending already shows the person.

So Greek could simply say:

• αλλά τα προτιμώ στο γιαούρτι

and it would still mean but I prefer them in yogurt.

But εγώ is added here for contrast:

• Η μαμά μου ... αλλά εγώ ...
• My mom ... but I ...

So εγώ is not required for grammar; it is used for emphasis and contrast.

Τα means them here.

It refers back to:

• καρύδια και αμύγδαλα

So:

• τα προτιμώ = I prefer them

This is a direct object pronoun, and in Greek these short object pronouns usually come before the verb.

Because both nouns it refers to are neuter plural:

• καρύδια = neuter plural
• αμύγδαλα = neuter plural

So the pronoun that replaces them is also neuter plural:

• τα = them

This is very natural in Greek. Since these are things, not people, neuter plural is exactly what you would expect.

Because Greek weak object pronouns normally come before the verb.

Compare:

• τα προτιμώ = I prefer them
• τον βλέπω = I see him
• την ξέρω = I know her

This is one of the main word-order patterns learners need to get used to.

If you wanted a stronger, more emphatic form, Greek could use a fuller pronoun like αυτά, but that is not the neutral pattern here. The normal everyday structure is τα προτιμώ.

Κέικ is a loanword, originally from English cake. In Modern Greek it is commonly used as a neuter noun:

• το κέικ
• στο κέικ

It is often treated as indeclinable, meaning its basic form stays the same and the article shows its role:

• το κέικ
• του κέικ
• στο κέικ

So even though the word itself is borrowed, it behaves perfectly naturally in a Greek sentence.

Yes, Greek word order is more flexible than English word order, but not completely free.

The sentence as written is natural because it highlights a contrast:

• Η μαμά μου βάζει ... αλλά εγώ τα προτιμώ ...

This gives a clear she does X, but I prefer Y structure.

Some parts are more movable than others, but the clitic pronoun τα usually stays before the verb:

• εγώ τα προτιμώ
• not normally εγώ προτιμώ τα in this meaning

So Greek allows flexibility for emphasis, but certain small pronouns still follow fixed patterns.

Literally, yes, it is in the yogurt.

But in natural English, depending on the context, you might also say:

• with yogurt
• mixed into yogurt
• on yogurt

Greek σε is broader than any one single English preposition, so the exact best translation depends on the situation. In this sentence, the idea is simply that the speaker prefers the walnuts and almonds as part of yogurt rather than as part of cake.