Этот чизкейк оказался мягче, чем вчерашний кекс.

Оказался comes from оказаться, which often means to turn out to be.

So:

• Этот чизкейк был мягче... = This cheesecake was softer...
• Этот чизкейк оказался мягче... = This cheesecake turned out to be softer...

Using оказался adds the idea of a result, discovery, or surprise. It suggests that after trying it or checking it, the speaker realized it was softer than the cupcake from yesterday.

Also, оказался is masculine singular past tense, agreeing with чизкейк, which is a masculine noun in Russian.

Мягче is the comparative form of мягкий (soft), so it means softer.

• мягкий = soft
• мягче = softer

In Russian, short comparative forms like мягче, быстрее, лучше, интереснее are very common and often more natural than using более + adjective.

So:

• мягче = the normal, natural way to say softer
• более мягкий can also mean softer, but it is usually more formal or less direct in everyday speech

You would not use мягкий here because the sentence is making a comparison.

Чем means than in comparisons.

So:

• мягче, чем вчерашний кекс = softer than yesterday’s cupcake

This is the standard Russian pattern:

• X + comparative + чем + Y

Examples:

• старше, чем я = older than me
• лучше, чем раньше = better than before
• интереснее, чем книга = more interesting than the book

Yes. Вчерашний means yesterday’s or from yesterday.

So:

• вчерашний кекс = yesterday’s cupcake / the cupcake from yesterday

Russian very often uses adjectives like this where English may use a noun phrase:

• сегодняшняя газета = today’s newspaper
• завтрашняя встреча = tomorrow’s meeting
• вчерашний хлеб = yesterday’s bread

Here вчерашний agrees with кекс:

• masculine
• singular
• nominative

Both main noun phrases are in the nominative case here.

• Этот чизкейк — nominative singular
• вчерашний кекс — nominative singular

Why?

1. Этот чизкейк is the subject of the sentence.
2. After чем in a comparison like this, Russian often uses the nominative as well:
   • мягче, чем вчерашний кекс

So the comparison is built with:

• subject in nominative
• comparative adjective/adverb
• чем + nominative phrase

Этот is the masculine singular form of this.

Since чизкейк is masculine, the demonstrative must agree with it:

• этот чизкейк = this cheesecake
• эта книга = this book
• это окно = this window
• эти люди = these people

Это can sometimes mean this/it/that is, but it is not the adjective form used before a masculine noun here.

So:

• Этот чизкейк = correct
• Это чизкейк would mean something more like This is a cheesecake

In the past tense, Russian verbs agree in gender and number with the subject.

The subject is чизкейк, which is masculine singular, so the verb is:

• оказался — masculine singular past

Compare:

• чизкейк оказался — the cheesecake turned out...
• книга оказалась — the book turned out...
• письмо оказалось — the letter turned out...
• пирожные оказались — the pastries turned out...

So the ending -ся is part of the verb, and the masculine past ending is shown in оказал-ся.

Yes, чизкейк is a borrowed word used in Russian, from English cheesecake.

Russian borrows many food words and adapts them to Russian grammar. Even though it is borrowed, it behaves like a normal Russian masculine noun:

• этот чизкейк
• вкусный чизкейк
• нет чизкейка
• люблю чизкейк

So learners should treat it as a regular masculine noun in usage.

Yes, Russian word order is flexible, although the original version is the most neutral and natural.

Neutral order:

• Этот чизкейк оказался мягче, чем вчерашний кекс.

Possible variations:

• Этот чизкейк мягче оказался, чем вчерашний кекс.
• Мягче, чем вчерашний кекс, оказался этот чизкейк.

These alternatives may sound more marked, literary, or contrastive depending on context.

For most learners, the best default pattern is the straightforward one:

• subject + verb + comparative + чем + comparison

It can, but it depends on context.

Кекс often refers to a cake-like baked item, sometimes closer to:

• sponge cake
• pound cake
• muffin-like cake
• cupcake

In translations, cupcake may be used, but кекс is not always exactly the same as the English word cupcake. It is a broader Russian word for a certain kind of sweet baked good.

So if the meaning has already been given as cupcake, that is fine for understanding the sentence, but it is good to know the match is not always perfect.

Sometimes Russian also uses the comparative with the genitive case instead of чем, especially in shorter or more compact phrases.

For example:

• Этот чизкейк мягче вчерашнего кекса.

This also means This cheesecake is softer than yesterday’s cupcake.

But in your sentence, the version with чем is very clear and common:

• мягче, чем вчерашний кекс

For learners, comparative + чем + noun phrase is often the easiest and safest pattern to use.