How do you say would like a cookie in Russian?

There are a few ways to say "would like a cookie" in Russian, depending on the level of formality and context:

Formal:

* Я хотел бы (я хотела бы) печенье. (Ya khotel by (ya khotela by) pechen'e.) - This is the most formal way to say it.

* Не могли бы вы дать мне печенье? (Ne mogli by vy dat' mne pechen'e?) - This means "Could you give me a cookie?"

Informal:

* Я хочу печенье. (Ya khochu pechen'e.) - This is a more casual way to say "I want a cookie."

* Можно печенье? (Mozhno pechen'e?) - This means "Can I have a cookie?"

With polite request:

* Не могли бы вы дать мне (хотелось бы получить) печенье? (Ne mogli by vy dat' mne (khotelos' by poluchit') pechen'e?) - This translates to "Could you give me (I would like to receive) a cookie?"

You can choose the most appropriate phrase based on the situation and your relationship with the person you're talking to.