Save glass jars with lids. I like Mason jars. I have a good supply of them and the deer decimated our tomato crop so I am not expecting to do a whole lot of canning any time soon.
Microwave milk. This is very important: WITHOUT THE LID. Do not microwave metal unless your intent is to ruin your microwave and start a fire in one fell swoop.
Shake jar. This is also very important: WITH THE LID.
Add coffee or espresso or cocoa or tea and maple syrup or agave or cinnamon or nutmeg or other flavorings to taste. Drink hot or pour over a generous amount of ice. If you are going to pour over ice, you want to make your coffee/espresso/cocoa/tea twice as concentrated.
I think this would work with any milk substitute with a decently high fat content. I like it with regular milk, coconut milk, or cashew milk. Skim milk or almond milk works and will taste fine, but is not going to froth nearly as well.
Fresh whipped cream is an ideal topping. Pure heavy whipping cream in a jar WITH THE LID ON and shake until it is whipped. Set aside and then top the latte. Any extra will go perfectly with some fresh berries. Easy.