Aunque ya es tarde, sigo cocinando con el delantal puesto porque quiero terminar la cena.

Both are possible, but they mean slightly different things.

• Aunque ya es tarde uses the indicative because the speaker treats it’s already late as a real, known fact.
• Aunque ya sea tarde uses the subjunctive and can sound more like even if it’s already late or although it may be late, depending on context.

In this sentence, the speaker clearly knows it is late, so es is the most natural choice.

In Spanish, es tarde is the fixed expression for it’s late.

• ser tarde = to be late in terms of time
• estar tarde is not used this way

So:

• Ya es tarde = It’s already late

This is just one of those expressions you learn as a set phrase.

Ya here means already.

So:

• Es tarde = It’s late
• Ya es tarde = It’s already late

It adds the idea that the time has reached a point that feels late, perhaps later than expected.

Both are grammatical, but they focus on different ideas.

• Estoy cocinando = I am cooking
  This just describes what is happening right now.
• Sigo cocinando = I’m still cooking / I continue cooking
  This emphasizes that the action has been going on and has not stopped.

In this sentence, sigo cocinando fits well because the speaker is saying that, although it’s late, they are still doing it.

After seguir, Spanish often uses seguir + gerund to mean to keep doing something or to continue doing something.

Examples:

• Sigo estudiando = I’m still studying
• Seguimos hablando = We kept talking
• Sigue lloviendo = It’s still raining

So sigo cocinando literally means I continue cooking, but in natural English it is often I’m still cooking.

Because Spanish often leaves out subject pronouns when the verb ending already makes the subject clear.

• sigo = I continue / I’m still
• quiero = I want

The -o ending tells you the subject is yo.

Including yo is possible, but it usually adds emphasis:

• Yo sigo cocinando... = I’m the one who’s still cooking...

Without emphasis, omitting the pronoun is more natural.

Literally, it means with the apron put on.

Here, puesto is the past participle of poner (to put), but in this kind of structure it acts like an adjective meaning:

• on
• being worn

So:

• llevar el delantal puesto
• estar con el delantal puesto

both suggest wearing the apron.

This is a very common pattern in Spanish:

• con la puerta cerrada = with the door closed
• con las luces encendidas = with the lights on
• con los zapatos puestos = with shoes on

Because puesto describes el delantal, so it agrees in gender and number with that noun.

• el delantal puesto — masculine singular
• la chaqueta puesta — feminine singular
• los zapatos puestos — masculine plural
• las gafas puestas — feminine plural

This agreement is very normal when a past participle is being used adjectivally.

Yes, delantal is normally a masculine noun in standard Spanish, so we say:

• el delantal

That is why the sentence has:

• el delantal puesto

A learner might expect clothing words to vary more, but here the noun is simply masculine and fixed.

In this sentence, it most naturally means finish making/preparing dinner.

Why? Because the speaker says:

• sigo cocinando
• quiero terminar la cena

Since they are still cooking, la cena here is understood as the dinner being prepared, not the act of eating it.

Spanish often allows this kind of shorthand:

• terminar la comida
• preparar la cena
• hacer la comida

The exact meaning comes from context.

Because porque is the conjunction meaning because.

Compare:

• porque = because
• por qué = why
• el porqué = the reason
• por que = a less common combination used in certain structures

In your sentence:

• porque quiero terminar la cena = because I want to finish dinner

Because the sentence begins with a subordinate clause:

• Aunque ya es tarde, ...

When a clause like this comes first, Spanish normally separates it from the main clause with a comma.

So this is standard punctuation:

• Aunque ya es tarde, sigo cocinando...

If the order were reversed, the comma would often disappear:

• Sigo cocinando aunque ya es tarde.

Yes, you could, but sigo cocinando sounds more natural and common in everyday speech.

Compare:

• sigo cocinando = very common, natural
• continúo cocinando = correct, but a bit more formal or literary in many contexts

For normal conversation, seguir + gerund is usually the best choice.

Yes, delantal is completely natural in Spain.

In other Spanish-speaking regions, you may also hear different words, such as:

• mandil in some countries

But delantal is standard Spanish and is widely understood. Since you mentioned Spanish from Spain, delantal is exactly what many learners would expect to hear.

Yes. Spanish is flexible, although some versions sound more natural than others.

For example:

• Aunque ya es tarde, sigo cocinando con el delantal puesto porque quiero terminar la cena.
  This is the original and sounds very natural.

You could also say:

• Sigo cocinando con el delantal puesto, aunque ya es tarde, porque quiero terminar la cena.

But this version feels a bit heavier. The original order is smoother because it presents:

1. the contrast (although it’s late),
2. the ongoing action (I’m still cooking),
3. the reason (because I want to finish dinner).

Grammatically, porque simply introduces the reason.

• Aunque ya es tarde = contrast
• porque quiero terminar la cena = reason/explanation

Whether it sounds like a real reason or an excuse depends on tone and context, not on the grammar itself. In neutral reading, it just means the speaker is explaining why they are still cooking.