Cette tarte est plus moelleuse que celle de la semaine dernière, mais le bord est moins croustillant.

Cette is a demonstrative adjective: it goes directly before a noun.

• cette tarte = this tart / this pie

Celle is a demonstrative pronoun: it replaces a feminine singular noun that has already been mentioned or is understood.

• celle de la semaine dernière = the one from last week

So instead of repeating cette tarte est plus moelleuse que la tarte de la semaine dernière, French uses celle to avoid repetition.

Because tarte is feminine singular.

The demonstrative pronouns must match the noun they replace:

• celui = masculine singular
• celle = feminine singular
• ceux = masculine plural
• celles = feminine plural

Since tarte is feminine singular, the correct form is celle.

Plus ... que is the basic pattern for more ... than.

• plus moelleuse que = softer / more tender than

Structure:

• plus + adjective + que
• plus + adverb + que
• plus de + noun + que

Examples:

• Cette tarte est plus moelleuse que l’autre.
• Il parle plus vite que moi.
• Elle a plus de patience que lui.

In your sentence, it compares the texture of one tart with another.

It works the same way as plus ... que, but it means less ... than.

• moins croustillant = less crispy
• moins croustillant que... = less crispy than...

In the sentence, the comparison is implied from the context:

• mais le bord est moins croustillant = but the crust/edge is less crispy

French does not always repeat the full comparison if it is already obvious.

French adjectives agree with the noun they describe.

• tarte is feminine singular, so:
  • moelleux becomes moelleuse
• bord is masculine singular, so:
  • croustillant stays croustillant

So:

• Cette tarte est plus moelleuse
• Le bord est moins croustillant

This is basic adjective agreement in French.

Moelleux / moelleuse usually describes something with a soft, tender, light, or moist texture.

For food, it can mean:

• soft
• fluffy
• tender
• moist

The best English choice depends on the food. With tarte, more tender or softer may fit naturally, but moelleuse often suggests a pleasant softness rather than simply being not hard.

So learners should know that it is a texture word, and its exact translation can shift with context.

Le bord literally means the edge or the rim.

In the context of a tart, it refers to the outer edge of the pastry. In English, that might sometimes be translated as:

• edge
• rim
• crust

It is not exactly the same as la croûte, which more specifically means the crust.

So le bord est moins croustillant means the outer edge of the tart is not as crisp.

Because French normally needs an article before semaine here.

• la semaine dernière = last week

After de, de + la stays de la:

• celle de la semaine dernière = the one from last week

You cannot normally say de semaine dernière in this context.

Many common time expressions in French place dernier / dernière after the noun:

• la semaine dernière = last week
• l’année dernière = last year
• le mois dernier = last month

This is just the standard pattern for these expressions.

By contrast, in some other cases dernier can come before the noun, but that often changes the nuance or sounds more literary/formal. For everyday time expressions like this, use:

• la semaine dernière
• le mois dernier
• lundi dernier

French usually repeats the verb more readily than English does.

The sentence has two linked statements:

• Cette tarte est plus moelleuse que celle de la semaine dernière
• mais le bord est moins croustillant

You could think of it as:

• This tart is softer than last week’s one, but the edge is less crispy.

Repeating est makes the second comparison clear and natural in French.

Yes, absolutely.

A fuller version could be:

• Cette tarte est plus moelleuse que celle de la semaine dernière, mais le bord est moins croustillant que celui de la semaine dernière.

That is grammatically correct, but it is heavier because it repeats information already understood. French often avoids unnecessary repetition when the comparison is obvious from context.

Because French uses demonstrative pronouns like celui / celle / ceux / celles to do that job.

English often says:

• the one
• the ones

French uses:

• celui = the one (masculine)
• celle = the one (feminine)
• ceux = the ones (masculine plural)
• celles = the ones (feminine plural)

So celle de la semaine dernière directly means the one from last week.

A simple pronunciation guide:

• Cette ≈ set
• tarte ≈ tart
• est ≈ eh
• plus moelleuse ≈ ploo mwah-luhz
• que ≈ kuh
• celle ≈ sel
• de la semaine dernière ≈ duh la suh-men der-nyair
• mais ≈ meh
• le bord ≈ luh bor
• est moins croustillant ≈ eh mwan kroo-stee-yan

A few useful notes:

• In careful speech, plus in a comparison is often pronounced plu or plys depending on context and speaker, but learners commonly hear plu before a consonant.
• Moins sounds like mwan.
• The end of croustillant is nasal: -llant sounds roughly like -yan, without a strong n sound.

Yes. Que has several uses, and one of them is than in comparisons.

In this sentence:

• plus moelleuse que = softer than

That is different from other uses such as:

• Je pense que... = I think that...

So learners need to identify que from the structure around it. After plus, moins, or aussi, it often means than / as.

Only if you want the opposite meaning.

• moins croustillant = less crispy
• plus croustillant = more crispy

So the sentence would change meaning completely. The original sentence contrasts two qualities:

• the tart itself is better/softer
• but the edge is less crispy

That contrast is expressed by mais and by switching from plus to moins.

Yes, cette is used before feminine singular nouns.

Demonstrative adjectives are:

• ce = masculine singular
• cet = masculine singular before a vowel sound
• cette = feminine singular
• ces = plural

Examples:

• ce gâteau
• cet abricot
• cette tarte
• ces tartes

Since tarte is feminine singular, cette is the correct form.