Decorate your buttercream icing with small bits of praline and pistachios to go on top of Pistachio Dacquoise.
Heat oven to 325 degrees. Spread nuts on baking sheet and toast for 6 to 8 minutes. Do not brown. Keep nuts warm. Lightly oil another baking sheet and set aside.
Combine water and sugar in a medium saucepan. Cook over medium-high heat, swirling pan, until mixture is a medium-amber color. Stir in nuts all at once.
Pour hot liquid onto prepared baking sheet and spread with a wooden spoon or oiled spatula. Let cool.
Grind half of praline to a coarse powder for buttercream; chop or crack remainder into small pieces for garnish.