Preheat oven to 225°. Line 2 heavy large baking sheets with parchment paper. Using small bowl or can as guide, trace three 4-inch-diameter circles on parchment on each baking sheet; turn parchment over (circles will show through).
Brush parchment with melted butter.
Whisk powdered sugar and 2 tablespoons sugar in small bowl to blend. Using electric mixer, beat egg whites and salt in large bowl until foamy and beginning to hold soft peaks. Slowly beat in 1/2 cup sugar; continue beating until whites are stiff and shiny. Fold in powdered sugar mixture, then chocolate. Spoon meringue by generous 1/2 cupfuls into center of each circle. Using back of spoon, spread meringue to edge of circle and indent center to form shallow bowl.
Bake meringues until crisp, about 1 hour 30 minutes.
Place baking sheets on racks; cool completely. (Meringues can be prepared 4 days ahead. Store airtight at room temperature.)
Bring cream, water and sugar to boil in medium saucepan over medium heat, stirring to dissolve sugar. Reduce heat to low; add chocolate.
Whisk until melted.
Remove from heat; stir in extract. (Can be prepared 1 day ahead. Cover and refrigerate. Rewarm sauce over low heat before using.)
Place 1 meringue in center of each plate. Top with scoops of ice cream.
