Vi hadde glemt bakepapiret, men naboen lånte oss både bakepapir og en ekstra kjele.

Hadde glemt is the past perfect, literally had forgotten. It shows that the forgetting happened before the next past event in the sentence.

So the timeline is:

• first: we forgot the baking paper
• then: the neighbor lent us some

That is why Norwegian uses hadde glemt here.

Compare:

• Vi glemte bakepapiret. = We forgot the baking paper.
• Vi hadde glemt bakepapiret. = We had forgotten the baking paper.

The second version fits especially well when another past event follows.

After hadde, Norwegian uses the past participle, not the simple past.

So:

• å glemme = to forget
• glemte = forgot
• glemt = forgotten

That gives:

• Vi glemte ... = We forgot ...
• Vi hadde glemt ... = We had forgotten ...

This is the same basic pattern as in English:

• forgot
• had forgotten

This is a very natural thing in Norwegian.

• bakepapiret = the baking paper
• bakepapir = baking paper / some baking paper

In the first part, bakepapiret refers to the specific baking paper they were supposed to have for the situation. The definite form can be used when the item is understood from context.

In the second part, lånte oss både bakepapir og en ekstra kjele, the word bakepapir is used more like a material or uncountable noun: some baking paper.

So the contrast is roughly:

• We had forgotten the baking paper
• but the neighbor lent us baking paper

This is not strange in Norwegian at all.

Literally, naboen means the neighbor.

But in actual use, Norwegian often uses the definite form where English might say:

• the neighbor
• our neighbor
• or even a neighbor

depending on context.

Here, naboen probably refers to the neighbor that is relevant in the situation, so English might naturally translate it as the neighbor or our neighbor.

This is common in Norwegian: the definite form often points to someone or something that is already identifiable from the situation, even if it has not been mentioned earlier in the sentence.

This is a very common learner question, because låne can correspond to both borrow and lend depending on the structure.

Here:

• naboen = subject
• lånte = lent/borrowed
• oss = us
• både bakepapir og en ekstra kjele = both baking paper and an extra pot

Since the neighbor is giving something to us temporarily, lånte oss means lent us.

So:

• Vi lånte en kjele av naboen. = We borrowed a pot from the neighbor.
• Naboen lånte oss en kjele. = The neighbor lent us a pot.

Many learners also learn låne bort for lend out, because it makes the “lend” meaning clearer:

• Naboen lånte bort en kjele til oss. = The neighbor lent a pot to us.

But your sentence with lånte oss is completely natural.

Because oss is the indirect object here.

Norwegian often works like English in this pattern:

• The neighbor lent us a pot
• Naboen lånte oss en kjele

You can also express the receiver with a prepositional phrase in some cases, but with verbs like this, a direct indirect-object pronoun is very normal.

So:

• lånte oss en kjele = lent us a pot

This is similar to:

• ga oss en gave = gave us a gift
• sendte oss en pakke = sent us a package

Både ... og ... means both ... and ...

So:

• både bakepapir og en ekstra kjele = both baking paper and an extra pot

This structure is very common in Norwegian.

Examples:

• Hun liker både te og kaffe. = She likes both tea and coffee.
• Vi trenger både sukker og mel. = We need both sugar and flour.

Kjele is a noun that takes en in Bokmål:

• en kjele = a pot
• kjelen = the pot

So en ekstra kjele means an extra pot.

The adjective ekstra is convenient because it usually does not change form:

• en ekstra stol
• et ekstra rom
• ekstra stoler

So here, ekstra stays the same.

Because men joins two main clauses, and the second clause keeps normal main-clause word order:

• Vi hadde glemt bakepapiret
• men naboen lånte oss ...

So in the second clause, the order is:

• naboen = subject
• lånte = verb
• oss = object

This is different from some subordinate clauses in Norwegian, where the word order changes. But after men, you usually just get a new main clause.

Here it is being treated like a material / mass noun, much like paper in English.

So:

• bakepapir = baking paper / some baking paper

You are not counting individual units here. The sentence is talking about the substance or supply in general.

That is why the indefinite bare form sounds natural.

If you wanted to count pieces or rolls, you would usually need extra words, for example:

• et ark bakepapir = a sheet of baking paper
• en rull bakepapir = a roll of baking paper

Yes, it could, but the meaning would be slightly less precise.

• Vi glemte bakepapiret, men naboen lånte oss ...
• Vi hadde glemt bakepapiret, men naboen lånte oss ...

Both are understandable.

But hadde glemt is better if you want to clearly show that the forgetting had already happened before the neighbor helped. It gives the sentence a stronger sense of sequence and background.

So the original version is a good, natural choice.