While I understand the compulsion to brew odd things, I urge you to keep it as simple as possible for a while. Get to know the craft of brewing, the brewing process, and how it applies in your brewery, before you go making stuff like Chocolate Oatmeal Milk Stout. There are lots of different things going on in such a recipe that will not necessarily preclude
success, but will make it a lot harder to attain.
Take, for example, the oatmeal part of the name. Unless you're a mashing brewer - partial mash or all-grain - you cannot
use oats in your beer. Sure, you could just steep them, but all they'd add is foam-killing fat/lipids and amorphous glop. Not to put too fine a point on it, but what you want just isn't possible. As an extract brewer, you're better off eating the oatmeal then taking a sip of well-crafted, simple Stout you brewed yourself.
For a simple Stout you'll be happy with, I've this recipe
All I'm saying is get used to brewing before you make it complicated. Master chefs don't start with Toulouse cassoulet; they start with simple, master that, and work their way up. That way they're more assured of success when they try something complicated or create something new.
I see all too many new brewers come and go. The come wanting to brew some Frankenstein beer with weird flavors. They go because they don't succeed. If they'd brew simple things for a while first, they'd stick around, because they'd feel a lot better about their success rate!
Anyway, that's my advice. YMMV.