Preheat the oven to 350. Line a 10 inch cast iron pan with aluminum foil and spray the foil w/ cooking spray.
In a large mixing bowl, stir 1 1/2 cups of sugar into the melted butter. Beat in the eggs one at a time. Sift the flour and salt onto the batter. Add the flavoring and stir well. Pour the batter into the skillet. Top w/ the sliced almonds and the remaining 2 tbsp sugar. Bake until slightly brown on top, about 35 minutes. Cool in the skillet. When cool, use the foil to lift the shortbread from the skillet. Remove the foil before serving.