Learn Hardcore Spanish (Latin America): Me gusta poner almendras en mi yogur por la mañana. - I like to put almonds in my yogurt in the morning.

Me gusta poner almendras… = “Putting almonds… pleases me.”
Saying yo gusto would literally be “I please” (someone else), which is almost never how we talk about personal likes in Spanish. You’d need to say who you please: Yo le gusto a ella = “She likes me.”

Why is gusta singular if almendras is plural?

Because the real subject of the sentence is the verb phrase, not almendras.

Subject: poner almendras en mi yogur por la mañana (the action of putting almonds in my yogurt in the morning)
That whole action is treated as one thing, so gustar is used in the singular: gusta.

Compare:

Me gustan las almendras. – I like almonds. (subject = las almendras, plural → gustan)
Me gusta comer almendras. – I like to eat almonds. (subject = comer almendras, one action → gusta)

Can I also say A mí me gusta poner almendras en mi yogur por la mañana? What’s the difference?

Yes, it’s correct and very natural.

Me gusta poner almendras… – neutral.
A mí me gusta poner almendras… – adds emphasis on “me” (me, as opposed to someone else).

It’s like saying:

Me gusta… → I like…
As for me, I like… / I personally like… → A mí me gusta…

Why is poner in the infinitive? Could I say “me gusta pongo almendras”?

After gustar (when you’re talking about liking an action), Spanish uses the infinitive:

Me gusta poner almendras… – I like to put almonds… / I like putting almonds…

You cannot say me gusta pongo almendras. The options are:

Me gusta poner almendras en mi yogur. – I like to put almonds in my yogurt.
Me gusta que ponga almendras en mi yogur. – I like that I (or someone) put(s) almonds in my yogurt. (with subjunctive: ponga)

For your original meaning (your own habit), the infinitive poner is the right choice.

Could I use another verb like añadir, echar, or agregar instead of poner?

Yes, several verbs are possible, with slight style or regional differences:

poner almendras – very common and neutral: “put almonds (in).”
añadir almendras – “add almonds”; a bit more “formal/instructional,” common in recipes.
agregar almendras – also “add almonds”; often heard in Latin America.
echar almendras – literally “throw in almonds”; very common in everyday speech in many areas.

Example alternatives:

Me gusta añadir almendras en mi yogur por la mañana.
Me gusta echarle almendras al yogur por la mañana.

Why is there no article before almendras? Why not unas almendras?

In Spanish, when you talk about things in general or in a habitual action, you can use a bare plural without an article:

Me gusta poner almendras en mi yogur. – I like putting almonds in my yogurt (in general, some almonds).

You could say unas almendras, but it subtly changes the feel:

Me gusta poner unas almendras en mi yogur.
- Slight emphasis on “a few/some almonds,” almost like you’re thinking about a specific portion.

For a general habit, almendras without article is the most natural.

Why is it mi yogur and not mis yogures or el yogur?

All are possible, but they say slightly different things:

mi yogur – one yogurt that is mine (the one I’m about to eat now, or typically have).
mis yogures – several yogurts that are mine.
el yogur – “the yogurt,” in a more generic sense (the yogurt I usually eat, or yogurt as a concept in this routine).

In everyday speech, mi yogur is very natural when you’re picturing your usual bowl or cup of yogurt in the morning.

Is yogur masculine or feminine, and how is it spelled in Latin America?

Gender: masculine → el yogur
Traditional standard spelling (RAE): yogur
In much of Latin America, you’ll also see yogurt (influenced by English).

All of these are heard:

el yogur natural
el yogurt natural

Your sentence with mi yogur is perfectly correct and sounds neutral.

Why is the preposition en used: en mi yogur, and not a mi yogur or sobre mi yogur?

En is the normal, broad preposition for things inside or on/in something:

poner almendras en mi yogur – put almonds in/into my yogurt.

Alternatives:

sobre mi yogur – literally “on top of my yogurt”; focuses on the surface (they sit on top).
a mi yogur – here would sound strange; poner X a Y is not the usual pattern for ingredients.

So:

Use en for the general idea of adding ingredients to food/drinks:
- poner azúcar en el café, poner limón en el té, poner almendras en el yogur.

What’s the difference between por la mañana, en la mañana, and de la mañana?

All relate to time, but usage and feel differ:

por la mañana – “in the morning / during the morning.”
- Very common, sounds natural everywhere.
- Stresses the time period (sometime in the morning).
en la mañana – also “in the morning.”
- Heard a lot in Latin America, sometimes more than por la mañana.
- In Spain, por la mañana is more frequent and en la mañana can sound less natural in some regions.
de la mañana – usually used with a specific clock time:
- a las 7 de la mañana – at 7 in the morning.
- Not used alone to mean “in the morning” in general.

Your sentence with por la mañana is perfectly good and widely understood.
En la mañana would also sound normal in much of Latin America.

Could I move por la mañana or me gusta to other positions in the sentence?

Yes, Spanish word order is fairly flexible as long as you keep related words together. All of these are possible:

Por la mañana, me gusta poner almendras en mi yogur.
Me gusta, por la mañana, poner almendras en mi yogur. (a bit more marked/emphatic)
Me gusta poner almendras en mi yogur por la mañana. (your original)

The most natural alternatives are:

Por la mañana me gusta poner almendras en mi yogur.
Me gusta poner almendras en mi yogur por la mañana.

They mean essentially the same thing; it’s just a matter of emphasis and rhythm.

How would I say “I love putting almonds in my yogurt” instead of just “I like”?

Use encantar, which is stronger than gustar:

Me encanta poner almendras en mi yogur por la mañana.
- Literally: “Putting almonds in my yogurt in the morning delights me.”

In everyday speech, me encanta is the usual way to say “I love (doing something)” in the sense of really like it a lot.

How would I say “I like almonds in my yogurt” (focusing on the almonds as the thing I like, not the action of putting them)?

Then the thing you like is the almonds (as an ingredient), not the action of adding them:

Me gustan las almendras en mi yogur. – I like almonds in my yogurt.

Here:

Subject: las almendras (en mi yogur) → plural
Verb: gustan (agrees with almendras)
Indirect object: me (to me).

Does Me gusta poner almendras en mi yogur por la mañana mean I’m doing it right now?

No. The present simple in Spanish usually expresses:

general preferences
habits / routines

So your sentence means something like:

“I (generally) like to put almonds in my yogurt in the morning.”
“I like putting almonds in my yogurt in the morning (as a habit).”

For something happening right now, you’d use the progressive:

Estoy poniendo almendras en mi yogur. – I’m putting almonds in my yogurt (right now).

You could add your preference too:

Ahora estoy poniendo almendras en mi yogur; me gusta hacerlo por la mañana.