Learn Icelandic: Ég ætla að skella í eina gómsæta dýfu.

When paired with the preposition í, the phrasal verb skella í becomes a very common idiom meaning to throw together, whip up, or quickly prepare something. You will hear it used a lot with food, baking, or drinks, like throwing together a cake or a dip.

Since this lesson is about vera til í (to be up for something), how would I change this sentence to say 'I am up for whipping up a delicious dip'?

You would use að plus the infinitive after the phrase, making it: Ég er til í að skella í eina gómsæta dýfu. Notice how til í replaces ætla to change the meaning from a firm intention to a willingness.

Icelandic doesn't normally use an indefinite article like 'a' or 'an'. Why is the number one (eina) used here before the noun?

While Icelandic lacks a strict indefinite article, the word einn is often used colloquially before adjectives to mean 'a' or 'a certain' when you want to sound enthusiastic or emphasize the noun. It gives the sentence a natural flavor, much like saying 'I am going to make one amazing dip' in English.

Why is the phrase eina gómsæta dýfu in the accusative case?

The preposition í governs the accusative case in the idiom skella í. Because dýfa is a feminine noun, it becomes dýfu in the accusative, and both the pronoun eina and the strong adjective gómsæta must match it in gender, case, and number.