Today, I ate a PON DE RING of theon de Ring from Mister Donut.

I most like PON DE RING like the Pon de Ring donuts ofthe most at Mister Donut!

It i's because they're sweet and their chewy texture is delicious.

Now, they've released collaboration donuts with Mickey Mouse and Minnie Mouse, so I would like to eat those next time.

Today, I ate a PON"Pon DEe RING of theing" from Mister Donut.

Sometimes Japanese uses katakana for emphasis, or sometimes even English letters. However, in English, we don't really use capital letters for mere emphasis like that. Putting something in all caps is like shouting it mid-sentence, it's something we really rarely use.

I most like PON DE RING inPon De Ring is my favourite donuts of from Mister Donut!

Your original version was a very direct translation (and would need "of" instead of "in"), but it's much more natural to use the adjective "favourite" for this situation.

It is because the sweet and chewy texture is delicious.

Now, there is a collaboration with Mickey Mouse and Minnie Mouse, so I would like to eat that next time.

You can also say "Mickey and Minne Mouse". You go do the same when talking about married couples, or other people that are commonly treated as a pair.

Today, I ate a PON DE RING of thehad a pon de ring (donut) from Mister Donut.

We typically say "had" instead of "ate" or "drank" for food and drink. No need to capitalize the name of the donut.

I most like PON DE RING in donuts of Mister Donut!My favorite donut from Mister Donut is the pon de ring,

It is because it's sweet and, chewy texture is, and delicious.

Better to combine this line with the previous since you are immediately following with a "because" reasoning

Now, there is a collaboration with Mickey Mouse and Minnie Mouse, so I would like to eattry those next time.