Make the Crust

1. Preheat oven to 325°F (163°C). Line a 9-inch (23cm) springform pan with parchment paper in the bottom and grease the sides.
2. Combine the crust ingredients in a small bowl. Press the mixture into the bottom and up the sides of the springform pan.
3. Bake the crust for 10 minutes, then set aside to cool.
4. Cover the outsides of the pan with aluminum foil so that water from the water bath cannot get in (see how I prepare my pan for a water bath). Set prepared pan aside.

Make the Filling

1. Reduce oven temperature to 300°F (148°C).
2. In a large bowl, beat the cream cheese, sugar and flour on low speed until completely combined and smooth. Be sure to use low speed to reduce the amount of air added to the batter, which can cause cracks. Scrape down the sides of the bowl.
3. Add the sour cream, almond extract and amaretto and mix on low speed until well combined.
4. Add the eggs one at a time, mixing slowly to combine after each addition. Scrape down the sides of the bowl as needed to make sure everything is well combined.
5. Pour the cheesecake batter into the crust.
6. Place the springform pan inside another larger pan. Fill the outside pan with enough warm water to go about halfway up the sides of the springform pan. The water should not go above the top edge of the aluminum foil on the springform pan.
7. Bake for 1 hour 15 minutes. The center should be set, but still jiggly.
8. Turn off the oven and leave the door closed for 30 minutes. The cheesecake will continue to cook, but slowly begin to cool as well.
9. Crack the door of the oven for 20-30 minutes to allow the cheesecake to continue to cool slowly. This process helps prevent cracking.
10. Remove the cheesecake from the oven and water bath wrapping and refrigerate until firm, 5-6 hours or overnight.

Make the Mousse

1. When cheesecake has chilled and is firm, make mousse topping. Add heavy whipping cream, powdered sugar, amaretto and almond extract to a large mixing bowl and whip oh high speed until stiff peaks form. Set whipped cream aside.
2. In another bowl, beat cream cheese until smooth.
3. Gently fold whipped cream into cream cheese in two parts until well combined.
4. Remove cooled cheesecake from springform pan and place on a serving platter. Top the cheesecake with about half of the mousse, then use the remaining mousse to pipe a border around the edge of the cheesecake. The mousse will be a little softer at first, but firm up as it cools in the fridge.
5. Sprinkle cheesecake with sliced almonds and store in refrigerator until ready to serve.