Jag vispar ägg och mjölk i en skål när jag gör pannkakor.

Because jag vispar is the correct present-tense form.

In Swedish, most present-tense verbs end in -r:

• att vispa = to whisk
• vispar = whisk / am whisking

So:

• jag vispar = I whisk / I am whisking

Jag vispa is not correct standard Swedish for the present tense.

Both vispar and gör are in the present tense.

Swedish uses the present tense not only for something happening right now, but also for:

• habits
• routines
• general truths
• step-by-step descriptions

So this sentence can mean something like a habitual action:

• When I make pancakes, I whisk eggs and milk in a bowl.

That is very natural in Swedish.

Because Swedish often leaves out articles when talking about ingredients or substances in a general way.

So:

• ägg och mjölk = eggs and milk

This works especially well in cooking contexts. English often does the same:

• I whisk eggs and milk...

Also, mjölk is usually an uncountable noun, so no article is needed here.
And ägg in recipe-style language often appears without an article when you mean eggs as an ingredient rather than specific eggs.

Most likely plural in meaning: eggs.

A useful thing to know is that ägg has the same form in:

• singular indefinite: ett ägg = an egg
• plural indefinite: ägg = eggs

So the word form itself does not show the difference here. You understand it from context. In a cooking sentence like this, ägg will usually be understood as plural unless the context suggests just one egg.

I means in, and en skål means a bowl.

So i en skål literally means:

• in a bowl

That is the natural preposition because the ingredients are inside the bowl.

Why en? Because skål is a common-gender noun:

• en skål
• skålen
• skålar
• skålarna

Why not skålen? Because the sentence does not refer to one specific already-known bowl. It just means a bowl in general.

Because nouns in Swedish belong to grammatical genders, and skål happens to be a common-gender noun, so it takes en.

You simply have to learn nouns together with their article:

• en skål
• ett ägg

This is one of the most important habits in learning Swedish vocabulary.

När means when here.

It introduces a time clause:

• när jag gör pannkakor = when I make pancakes

So the sentence has:

• a main clause: Jag vispar ägg och mjölk i en skål
• a subordinate time clause: när jag gör pannkakor

Because Swedish needs an explicit subject in each clause.

So:

• Jag vispar ...
• när jag gör ...

Even though English also does this, learners sometimes wonder whether Swedish could omit the second jag. Normally it cannot here.

Each clause needs its own subject and verb:

• Jag vispar
• jag gör

Because in this subordinate clause, the normal order is:

• conjunction + subject + verb

So:

• när jag gör pannkakor

That is completely standard.

A very useful comparison:

• Jag vispar ägg och mjölk när jag gör pannkakor.
• När jag gör pannkakor vispar jag ägg och mjölk.

In the second version, the när clause comes first, so the main clause changes word order:

• vispar jag, not jag vispar

That happens because Swedish is a V2 language in main clauses.

Yes, lagar pannkakor is also possible, but gör pannkakor is very natural.

In Swedish:

• göra = make / do
• laga = cook / prepare food

With something like pancakes, göra pannkakor is common because you are making them from scratch.
Laga pannkakor is also understandable and natural in many contexts, especially if you are emphasizing cooking/preparing food.

So:

• gör pannkakor = very common
• lagar pannkakor = also possible

Because when people make pancakes, they usually make more than one.

So gör pannkakor naturally means:

• make pancakes

If you said gör en pannkaka, that would mean you are making one pancake.
The plural is the normal choice for the dish in general.

Yes. Swedish present tense often covers both ideas:

• I whisk
• I am whisking

The exact interpretation depends on context.

So Jag vispar ägg och mjölk i en skål när jag gör pannkakor can sound like:

• a general habit, or
• a description of what I do in the process

Swedish does not usually need a separate progressive form like English am whisking.

Yes, absolutely.

You can say:

• När jag gör pannkakor vispar jag ägg och mjölk i en skål.

That means the same thing, but the emphasis is slightly different.

Just remember the word order change in the main clause:

• När jag gör pannkakor vispar jag ... not
• När jag gör pannkakor jag vispar ...

That inversion is very important in Swedish main clauses.