Caramelized Pineapple Sundaes with Chocolate-Coconut Sauce

Line 8x8-inch baking pan with foil. Stir sugar and water in heavy small saucepan over medium-low heat until sugar dissolves. Increase heat and boil without stirring until syrup is deep amber color, occasionally brushing down sides of pan with wet pastry brush and swirling pan, about 7 minutes. Mix in nuts. Immediately pour mixture into prepared pan, spreading slightly. Cool completely. Peel foil off praline. Coarsely chop praline. (Can be made 1 week ahead. Store refrigerated in airtight container.)