Why does the cinnamon have to go in before the ice?
Ground cinnamon doesn't dissolve, it suspends. In a pitcher with syrup and cold brew you can stir it through the liquid so it distributes evenly. Dump it straight onto a cup full of ice and it clumps, floats, and lands as a gritty first sip. Same reason the caramel sauce goes in the pitcher instead of the cup.
Can I use dairy milk instead of oat?
Yes. There's no fruit juice in this build, so dairy is safe here. Oat is what we recommend because it keeps the body creamy without competing with the banana. Whole milk works fine. Skim will taste thin against the syrup and caramel.
What if I don't have cold brew concentrate?
Ten ounces of ready-to-drink cold brew from a pre-mixed keg or dispenser stands in for the 2 oz concentrate plus 8 oz water. Don't substitute hot-brewed coffee poured over ice. It's more acidic and it fights the banana instead of supporting it.