Combine cardamom pods with 1-1/4 cups sugar and water in medium saucepan. Cook and stir over high heat until mixture comes to a boil and sugar dissolves. Reduce heat to low; cover and simmer 30 minutes. Remove from heat; cool completely. Refrigerate 2 hours or up to 3 days.

Pour mixture through strainer into 3-quart pitcher; discard pods. Stir in lemon juice and Asti Spumante. Stir in additional sugar to taste. Serve over ice. Garnish, if desired.