In my opinion, the quick and easy explanation is to:
1. Buy an espresso machine (doesn't need to be fancy) so that you can make espressos. That, or learn to better use your moka pot, which should let you produce something like an espresso.
2. Get some decent beans. If you live somewhere that roasts their own coffee and sells it to customers (no, not Starbucks or your grocery store), and you drink coffee somewhat frequently (i.e. you can finish a bag in 2 weeks), then ask them to grind the coffee for you. That way, you'll have reasonably fresh coffee to make your cafe mochas with. Tell them it's to grind it for espresso. To make espresso, they tend to grind your coffee a bit finer than they would for filtered coffee, so it's important to tell them that you want to make espresso.
That, or buy a cheap-o conical burr grinder and buy whole coffee beans. Grind it yourself so that it's fresher. I use a
Hario Skerton manual grinder, which means I need to grind beans by hand. It takes more time and effort, but I don't drink coffee at home very often. I have an electric burr grinder at home, but I only use it to grind 1 week's worth of coffee beans to bring to work.
If you don't live near a decent source of coffee, then you can actually buy online. Many places will offer a service where they'll grind it for you, and then mail it to you. It's not the freshest coffee in existence, but it's 100x better than what you're doing now.
😛
Sometimes, they will advertise a coffee as an "espresso roast", which should make it easier for you to choose. Coffee meant for filtered coffee tends to be light or medium roast, whereas coffee to be used for espresso tends to be a medium or darker roast.
I'm not American, but I found a place called
Blue Bottle Coffee that's supposed to be really good. The info also seems clear, but I don't think they'll grind your coffee for you!!
I believe
Stumptown will grind coffee for you. They're also supposed to be good.
Again, I'm not American, but I found a list of coffee roasters here:
Best Coffee Roasters in America.
3. I'm not sure how much this matters for you, but perhaps using
Ghirardelli chocolate would give you great results. That, or
Dutch-process cocoa powder like
Guittard Cacao Rouge Cocoa Powder.