Preheat your oven to 350°F (175°C).
Cream together the unsalted butter and confectioners' sugar until light and fluffy. Add in almond extract and salt, mixing until combined. Gradually stir in the all-purpose flour until the mixture forms a dough.
Press the shortbread dough evenly into the bottom of a greased 9x9 inch baking pan.
Bake in the preheated oven for about 20 minutes, or until the edges are lightly golden.
Melt the chopped semi-sweet chocolate and unsalted butter in a double boiler or microwave-safe bowl. Stir until smooth, then remove from heat and mix in sweetened condensed milk and almond extract.
Pour the fudge mixture over the cooled shortbread base, spreading it evenly.
Sprinkle the sliced toasted almonds over the fudge layer, pressing them in gently.
Return the pan to the oven and bake for an additional 25-30 minutes, or until the fudge is set but still soft in the center.
Allow to cool completely in the pan before slicing into squares or bars.