Bring the mixture to a gentle simmer over medium heat, stirring until the sugar fully dissolves. Once simmering, reduce heat to low and let steep for 5 minutes to extract lavender flavor — do not boil vigorously.

Cool and strain

Remove from heat and let the syrup steep another 10 minutes off the heat for stronger aroma. Strain the syrup through a fine mesh sieve or cheesecloth into a heatproof container, pressing on the lavender to extract liquid. Stir in 1/2 teaspoon vanilla extract if using. Let cool to room temperature, then refrigerate until chilled. Yield: about 1 to 1 1/4 cups syrup.

Coffee

Brew espresso or strong coffee

Pull two shots (about 2 oz total) of espresso. If you don't have an espresso machine, brew 2 oz strong coffee (use double-strength pour-over or a concentrated Moka pot brew). If using instant or regular coffee grounds, bloom the grounds with 2 tablespoons hot water first and then pull the brew so the coffee is very concentrated. Chill slightly (espresso can be used warm; will be cooled when poured over ice).

Milk & Assembly

Prepare glass

Fill a 16-oz (about 475 ml) glass with 1 cup ice cubes.

Add lavender syrup

Pour 2 tablespoons lavender simple syrup over the ice. Taste and adjust: add an additional 1/2 to 1 tablespoon if you prefer it sweeter or more floral.

Add milk

Pour 1 3/4 cups cold milk over the ice and syrup. Stir gently to combine the syrup and milk.

Add coffee

Slowly pour the two shots of espresso over the top. This will create a layered look; if you prefer fully combined, stir gently once after pouring.

Garnish and serve

Garnish with a small sprig of fresh lavender and a light pinch (about 1/4 tsp) of dried lavender buds on top if desired. Serve with a straw and a stirrer. Enjoy chilled.