Chill your champagne well. Pop the bottle in the fridge for at least 3 hours, or in an ice bucket for 30 minutes. Cold bubbles taste fresher and foam less when poured.

Make the raspberry syrup. In a small saucepan, combine raspberries, sugar, and water. Bring to a gentle simmer over medium heat, stirring until the sugar dissolves, about 3–4 minutes.

Mash and steep. Lightly mash the berries with a spoon. Remove from heat and let the mixture sit for 10 minutes to deepen the flavor.

Strain. Pour the syrup through a fine mesh strainer into a bowl or jar, pressing to extract the juices. Discard the seeds. Stir in lemon juice if using. Let it cool completely.

Speed-cool if needed. Place the jar of syrup in a bowl of ice water, stirring occasionally, until cold.

Assemble the drink. Add 1–2 teaspoons of raspberry syrup to each flute. Adjust to your sweetness preference.

Top with champagne. Tilt the glass and pour slowly to preserve bubbles. Aim for about 5 ounces per flute.

Garnish. Add 1–2 fresh raspberries to each glass. A small mint leaf is a nice touch, but optional.

Serve immediately. This drink is best enjoyed right after pouring, while the bubbles are lively.