In a large jar, combine coarsely ground coffee with cold water, stirring well to ensure all coffee grounds are saturated. Cover the jar and place it in the refrigerator, allowing it to steep for at least 12 hours.

In a separate bowl, add fresh blackberries and sage leaves, then drizzle in a bit of maple syrup. Muddle the mixture to release the juices, aiming for a vibrant blend. Divide into two tall glasses.

Carefully strain the cold brew concentrate through a fine mesh strainer into a clean pitcher, removing the coffee grounds.

Fill the glasses with ice cubes and pour the strained cold brew over them, creating a layered effect with the muddled mixture.

Warm the barista oat milk over low heat. Stir in maple syrup and whisk until creamy and frothy.

Spoon the frothy oat milk over each drink, garnish with sage leaves and blackberries. Serve and enjoy!