In recipes, instructions and so on, the infinitive can be used [instead of][1] the imperative form. That's why the verb is at the end of the sentence, as usual for infinitives.

As you say, the command form would be

> Kochen Sie die Nudeln! Schneiden Sie den Schinken in Streifen! ...

(note the pronoun), but this is often perceived as too strong for instructions or recipes. 

In older recipes, you'll also see an impersonal construction along the lines of 

> Man nehme Nudeln und koche sie. Dann nehme man Schinken und  schneide ihn klein. ...

There are other replacement forms for the imperative, see e.g. [Canoo][2] (in English) or [Wikipedia][3] (in German)


  [1]: https://de.wikipedia.org/wiki/Imperativ_(Modus)#Infinitiv
  [2]: http://canoonet.eu/services/OnlineGrammar/Wort/Verb/Modi/Imperativ.html?lang=en
  [3]: https://de.wikipedia.org/wiki/Imperativ_(Modus)#Ersatzformen_des_Imperativs