• 2 tablespoons cold water
  
• 1 3/4 teaspoons powdered gelatin
  
• 1 1/2 cups whole milk
  
• 1/4 cup plus 3 tablespoons sugar
  
• Pinch of salt
  
• 1 1/2 cups low-fat buttermilk
  
• 2 teaspoons powdered matcha green tea
  

In a small bowl, sprinkle the gelatin over the 2 tablespoons of water. Let stand for 5 minutes, until the gelatin softens.

In a medium saucepan, combine the milk, sugar and salt and warm over moderate heat, stirring to dissolve the sugar, about 3 minutes. Remove from the heat and whisk in the gelatin until completely dissolved, then whisk in the buttermilk. Pour 1 cup of this mixture into a glass measuring cup; cover and refrigerate until ready to use.

In a small bowl, whisk the green tea powder with 1/4 cup of the remaining buttermilk mixture until dissolved. Pour the dissolved green tea into the buttermilk mixture in the saucepan and whisk well.

Pour the green tea mixture into four 8-ounce glasses and refrigerate until just set, about 3 hours. Melt the 1 cup of refrigerated buttermilk mixture in a microwave oven until pourable but still cold, about 15 seconds. Top each panna cotta with the buttermilk mixture. Cover and refrigerate until firm, at least 3 hours longer.