Line an 8x8 or 9x9 inch square pan with aluminium foil leaving an overhang on each side.
In a large bowl, place the chopped semi-sweet and dark chocolate and set aside.
If using a candy thermometer, clip the thermometer to the side of a large heavy-bottom saucepan. Add the butter, sugar, whipping cream, marshmallow cream and salt to the sauce pan and heat over medium heat while stirring with a heat-proof rubber spatula or wooden spoon. Once melted allow the mixture to boil for 5-10 minutes while stirring until it reaches between 235F-240F degrees, or a soft ball is formed using the cold water test.
Remove from the heat and pour the sugar mixture over the chopped chocolate. Stir the mixture with your wooden spoon or rubber spatula and add in the salt and up to 4 tablespoons of amaretto.
Pour the mixture into your prepared pan and sprinkle with sliced almonds. Allow to harden at room temperature. Once the fudge is no longer hot, you can cover it and continue to harden in your refrigerator. After its hardened, remove the foil & fudge from the pan and cut into small squares.