Heat oven to 350°F. Spray bottom only of 13x9-inch pan with nonstick cooking spray. In large bowl, combine brownie mix, oil, 1/4 cup amaretto and eggs; beat 50 strokes with spoon. Stir in almonds. Spread in sprayed pan. Bake at 350°F. for 28 to 30 minutes. Place pan on wire rack; cool 45 minutes or until completely cooled.
In medium bowl, combine powdered sugar, butter, lemon juice, salt and 5 teaspoons amaretto; beat until fluffy, adding remaining amaretto if necessary for desired spreading consistency. Spread frosting over cooled brownies. Cut into squares; top each with almond.