Para el desayuno, me gusta el queso crema con una rebanada de pan.

Because gustar works differently from to like in English.

In Spanish, gustar literally works more like to be pleasing to. So:

• me gusta = it pleases me
• me = to me
• gusta = is pleasing

So in this sentence, the thing being liked is el queso crema con una rebanada de pan, and me shows who likes it.

That is why Spanish says:

• Me gusta el queso crema...

not

• Yo gusto...

Yo gusto would usually mean something very different, more like I am pleasing / I am liked, and it is not what you want here.

In Spanish, meals often take the definite article:

• el desayuno
• la comida
• la cena

So para el desayuno is a normal way to say for breakfast.

Spanish often uses the article where English does not. Compare:

• Desayuno a las ocho. = I have breakfast at eight.
• Durante el desayuno... = During breakfast
• Para el desayuno... = For breakfast

You could also hear:

• Para desayunar...

which means for breakfast / to have for breakfast and is also very natural.

After gustar, Spanish usually uses the definite article when talking about things in a general sense.

So:

• Me gusta el queso crema.
• Me gusta el café.
• Me gustan las fresas.

This does not necessarily mean a specific individual cream cheese. It often just means I like cream cheese in general.

English often drops the article in these cases, but Spanish normally keeps it.

It is understandable, but in Spain you will also very often hear:

• queso de untar = spreadable cheese
• sometimes brand names used generically, depending on context

So queso crema is fine and understandable, but queso de untar may sound a bit more typically Spain-based in everyday speech.

Because the grammatical subject is singular.

Here, the thing that is pleasing is understood as one item or one food combination:

• el queso crema con una rebanada de pan

Since that is singular, Spanish uses:

• gusta

You use gustan when the thing liked is plural:

• Me gustan las tostadas.
• Me gustan el queso crema y las fresas.

So gusta is correct here.

Because una rebanada de pan means a slice of bread.

The structure is:

• rebanada = slice
• de pan = of bread

So Spanish is building the phrase the same basic way as English:

• a slice of bread

The word con means with, so the sentence presents cream cheese together with a slice of bread.

After a measure word like rebanada, Spanish usually uses de + noun without an article when speaking generally.

So these are normal:

• una rebanada de pan
• un vaso de agua
• una taza de café

You would only add an article if you meant a specific bread:

• una rebanada del pan que compré ayer = a slice of the bread I bought yesterday

So de pan is the normal generic form.

Yes, but the meaning changes slightly.

• con pan = with bread, in a general sense
• con una rebanada de pan = with one slice of bread

So una rebanada makes it more specific and countable.

If you just want the general idea, con pan is perfectly possible. If you want to say exactly a slice of bread, then una rebanada de pan is the right choice.

Here para means something like for or as in the sense of as a breakfast choice.

• Para el desayuno = for breakfast

This sounds like you are introducing what you like to eat at that meal.

If you say en el desayuno, it means more literally at breakfast / during breakfast, which is possible in some contexts, but here para el desayuno sounds more natural for expressing a food preference.

Also very natural is:

• Para desayunar, me gusta...

It is not absolutely required, but it is very natural.

Para el desayuno is an introductory phrase, and Spanish often places a comma after this kind of opener, especially in writing:

• Para el desayuno, me gusta...

Without the comma, many people would still understand it perfectly:

• Para el desayuno me gusta...

So the comma is mainly helping readability and rhythm.

Yes. Spanish word order is more flexible than English word order.

For example, these are all possible:

• Para el desayuno, me gusta el queso crema con una rebanada de pan.
• Me gusta el queso crema con una rebanada de pan para el desayuno.
• El queso crema con una rebanada de pan me gusta para el desayuno.

The first version is the most neutral and clear for a learner. The others may sound more marked or place emphasis differently, but they are still understandable.

Yes.

• Me gusta... = normal, neutral
• A mí me gusta... = adds emphasis, contrast, or clarity

For example:

• A mí me gusta el queso crema, pero a mi hermano no.

The a mí is optional because me already tells us who likes it. It is added when you want emphasis or contrast.