Chocolate Amaretto Mousse Pie
["1 (12 oz.) pkg. semi-sweet chocolate chips", "1/4 c. (1/2 stick) butter", "1 (14 oz.) can sweetened condensed milk", "1/4 tsp. salt", "1/4 c. water", "1/4 c. Amaretto liqueur", "2 c. heavy cream", "sliced almonds (for garnish, optional)"]
["Line a 9-inch pie plate with aluminum foil; press the foil firmly against the surface of the plate, making the foil as smooth as possible.", "Melt 1 cup of the chocolate pieces with 2 tablespoons of the butter.", "Pour into foil-lined plate and quickly smooth over the bottom and up the side.", "Place in freezer until it is firm, about 30 minutes."]
["semi-sweet chocolate chips", "butter", "condensed milk", "salt", "water", "liqueur", "heavy cream", "almonds"]