Morgens esse ich gern Haferbrei mit warmen Äpfeln.

Here morgens means in the mornings / every morning / in the morning in a habitual sense.

The -s is part of an adverbial form that is very common with times of day:

• morgens = in the morning(s)
• abends = in the evening(s)
• nachts = at night
• mittags = at noon / around lunchtime

So Morgens esse ich ... sounds like a general routine, not just one specific morning.

A close alternative is am Morgen, but that often sounds a bit more like in the morning as a time reference, while morgens is especially natural for habits.

German main clauses follow the verb-second rule: the finite verb must be in the second position.

In the basic order, you could say:

Ich esse morgens gern Haferbrei ...

But in your sentence, Morgens has been moved to the front for emphasis. Once that happens, the verb still has to stay second, so ich comes after it:

• Morgens = position 1
• esse = position 2
• ich = then comes next

So:

• Ich esse morgens ...
• Morgens esse ich ...

Both are correct.

Gern means gladly / with pleasure / like to.

German often uses gern with a verb where English would use like + verb:

• Ich esse gern Haferbrei. = I like eating porridge.
• literally: I gladly eat porridge.

This is different from mögen:

• Ich mag Haferbrei. = I like porridge.
• Ich esse gern Haferbrei. = I like to eat porridge.

In many everyday situations, gern is the most natural choice when talking about activities.

Because Haferbrei is being talked about in a general sense, like a food category.

German often leaves out the article with foods, drinks, and other uncountable or general nouns:

• Ich trinke Kaffee.
• Sie isst Brot.
• Wir essen Haferbrei.

If you meant a specific serving, an article could appear:

• Ich esse den Haferbrei. = I’m eating the porridge / that porridge.
• Ich esse einen Haferbrei. = possible in some contexts, but less natural unless you mean a portion.

So in your sentence, no article is the normal choice.

Because mit always takes the dative case.

So after mit, both the article pattern and the adjective ending have to match the dative. In the plural, that gives:

• warme Äpfel = nominative/accusative plural
• mit warmen Äpfeln = dative plural

The adjective warm becomes warmen because it is describing a plural noun in the dative.

So:

• Ich esse warme Äpfel.
• Ich esse Haferbrei mit warmen Äpfeln.

That is a very common dative plural pattern.

In the dative plural, many German nouns add -n if they do not already end in -n or -s:

• die Äpfel → mit den Äpfeln
• die Kinder → mit den Kindern
• die Bücher → mit den Büchern

So in your sentence:

• base plural: Äpfel
• after mit (dative plural): Äpfeln

That -n belongs to the noun, while the -en in warmen belongs to the adjective.

In German, all nouns are capitalized.

So:

• Haferbrei is a noun
• Äpfeln is a noun

But:

• warmen is an adjective
• gern is an adverb

That is why the nouns begin with capital letters and the other words do not.

Also, Morgens is capitalized here because it is the first word of the sentence. In the middle of a sentence, it would normally be morgens.

Yes, absolutely.

Both are correct:

• Morgens esse ich gern Haferbrei mit warmen Äpfeln.
• Ich esse morgens gern Haferbrei mit warmen Äpfeln.

The difference is mainly emphasis:

• Morgens ... puts the time first, so it highlights in the mornings
• Ich ... starts more neutrally with I

German word order is flexible in this way, as long as the finite verb stays in second position.

Most naturally, it describes a habit or regular routine.

That is because:

• morgens usually suggests something repeated
• the present tense in German often covers habitual actions

So the sentence is understood as something like:

• In the mornings, I like to eat porridge with warm apples.

If you wanted to make it clearly about what is happening right now, German would usually add something like gerade:

• Ich esse gerade Haferbrei mit warmen Äpfeln.

Yes, Haferbrei is a normal German word. It literally means something like oat porridge.

You may also hear:

• Porridge — used in German too, especially in packaging, cafés, or modern food contexts
• Hafermüsli — not the same thing; this means oat muesli, not cooked porridge

So Haferbrei is a good, clear everyday German choice for this sentence.