La torta fatta in casa è migliore di quella comprata al negozio.

Because fatta agrees with torta, which is feminine singular.

• torta = feminine singular
• fatta is the past participle of fare, used here like an adjective
• When a past participle is used adjectivally in Italian, it usually agrees in gender and number with the noun it describes

So:

• torta fatta = cake made / made cake
• not torta fatto, because fatto is masculine singular

It is a past participle phrase that describes la torta.

You can think of it as:

• la torta [che è stata] fatta in casa
• literally: the cake [that was] made at home

Italian often shortens relative clauses this way, especially when the meaning is clear.

So instead of saying:

• La torta che è stata fatta in casa...

Italian very naturally says:

• La torta fatta in casa...

This is very common.

Because Italian often expresses this idea with a phrase rather than a single adjective.

• fatto in casa / fatta in casa = homemade
• literally: made in the home

This is one of the most common and natural ways to say homemade in Italian.

You may also see:

• casalingo / casalinga

but fatto in casa is extremely common and often the most straightforward choice.

In this expression, fatto in casa is the standard idiomatic way to say homemade.

Broadly speaking:

• a casa often means at home
• in casa often suggests in the house / in the home

But in many expressions, usage is just idiomatic, and fatto in casa is the set phrase learners should remember.

So although a casa and in casa can overlap in some contexts, here in casa is the natural choice.

Because migliore is the normal comparative form of buono in many contexts.

• buono = good
• migliore = better

So:

• è migliore di... = is better than...

Italian can sometimes use più buono, especially when talking very directly about taste, but migliore is generally more standard and broader in meaning.

Compare:

• Questa torta è migliore. = This cake is better.
• Questa torta è più buona. = This cake tastes better / is tastier.

Both can be possible, but migliore is a very natural choice here.

Because in comparisons, Italian often uses di after a comparative adjective.

So:

• migliore di = better than
• più grande di = bigger than
• più interessante di = more interesting than

In this sentence:

• è migliore di quella... = is better than that one...

This is a standard comparison pattern in Italian.

Because quella works as a demonstrative pronoun here, meaning that one.

Instead of saying:

• La torta fatta in casa è migliore della torta comprata al negozio

Italian can shorten it to:

• La torta fatta in casa è migliore di quella comprata al negozio

Here quella stands for torta.

This avoids repetition and sounds very natural.

Because quella refers back to torta, and torta is feminine singular.

So the pronoun has to agree with the omitted noun:

• quella = feminine singular
• quello = masculine singular

Since the hidden noun is torta, only quella works here.

For the same reason as fatta: it agrees with the noun it describes, which is the implied torta.

The full idea is:

• quella comprata al negozio
• literally: that one bought at the store

Expanded, it could be:

• quella torta comprata al negozio
• or even
• quella torta che è stata comprata al negozio

Since torta is feminine singular, the participle is comprata, not comprato.

Al is a contraction of:

• a + il = al

This is very common in Italian.

Other examples:

• a + la = alla
• di + il = del
• in + il = nel

So al negozio literally means something like at/to the store, depending on context.

Because Italian and English do not always package location and source in the same way.

In Italian, comprare al negozio can naturally mean buying something at the store. In English, we often prefer from the store.

So:

• comprata al negozio = bought at the store / store-bought

It is a normal Italian way to describe where the purchase happened.

Yes. A fuller version would be:

• La torta fatta in casa è migliore della torta comprata al negozio.

This is completely correct.

Why della there?

Because:

• di + la = della

So when you repeat la torta, the comparison becomes:

• migliore della torta...

When you replace la torta with quella, you get:

• migliore di quella...

Both are correct; the version with quella is less repetitive.

The given word order is the most natural one, but Italian does allow some flexibility.

The sentence is built like this:

• La torta fatta in casa = subject
• è = verb
• migliore di quella comprata al negozio = comparison

You could rearrange things a little in special contexts, but for learners, this version is the best model to follow.

It is clear, natural, and idiomatic.

Because è is the verb is from essere, while e without an accent means and.

So:

• è = is
• e = and

The accent is important in writing because it distinguishes two different words.

Example:

• La torta è buona. = The cake is good.
• La torta e il pane. = The cake and the bread.