Make a concentrated brown sugar syrup by dissolving brown sugar in hot water at a 1:1 ratio, then cool completely before use. This ensures the syrup fully dissolves in cold drinks without grittiness and delivers superior sweetness compared to dissolving sugar directly in the cold beverage.

Shake the espresso, syrup, and oat milk together in a cocktail shaker with ice for at least 10-15 seconds to create the signature frothy, creamy texture that mimics the Starbucks version. This aerates the oat milk and creates a smooth, cohesive drink rather than separated layers.

Brew your espresso shots fresh and add them to the shaker while still hot to properly extract flavors and prevent a flat-tasting drink. Cold espresso loses its aromatic complexity and won't properly integrate with the other ingredients during shaking.

Mix cinnamon and vanilla with a small amount of the brown sugar syrup before adding to the shaker to create a fragrant paste that distributes evenly throughout the drink. This prevents cinnamon from clumping and ensures consistent spice flavor in every sip.

Use larger ice cubes or crushed ice in your shaker (not serving glass) to minimize dilution during shaking, then serve over fresh ice to maintain the intended sweetness and espresso intensity. The two-ice approach prevents over-watering while keeping the drink properly chilled.