Preheat the oven to 350F. Lightly spray a 9 inch springform pan. Wrap the bottom and sides with foil if you are worried about your pan leaking.
Put the 1 sleeve graham crackers* into the bowl of your food processor. Break them apart as you add them. Add 1/3 cup sliced almonds and process until they are fine, even crumbs. Add the melted 4 Tbsp unsalted butter and 1/2 tsp almond extract and pulse until everything is evenly moistened.
Press the crumbs firmly and evenly into the bottom of the pan. I like to use the bottom of a metal measuring cup to assist in getting the crumb crust tamped down. Note: I don't press crumbs up the sides of the pan, just on the bottom.
Bake the crust for 8 minutes. Set aside to cool.
Wipe out the bowl of your food processor and add 1 cup granulated sugar, 16 ounces brick style cream cheese, 16 ounces whole milk ricotta cheese, 1 tsp almond extract and 2 Tbsp all purpose flour. Pulse/process until smooth. Using the pulse helps make sure everything gets evenly distributed before you process smooth. Note: you can do this with electric beaters or a stand mixer if you prefer, but your cream cheese will have to be room temperature or you'll get lumps.
Process in the 1/2 cup sour cream and then the 4 large eggs, one at a time, beating in between each addition. Be sure to scrape down the sides of the bowl often to get everything well incorporated.
Turn the batter into the pan and spread out evenly. Set the pan on a baking sheet.
Bake for about 50-55 minutes, or just until the outside is set and the inside still wobbles a bit. Turn off the heat and leave the cheesecake in the oven for another hour with the door propped open.
Cool the cheesecake in the pan on a rack until room temperature, then refrigerate overnight.
Carefully remove cheesecake from pan (I run a thin offset spreading knife around the edges to loosen everything first.)
Serve topped with whipped cream and sliced almonds (I like to toast them first for extra flavor.)
Keep leftover cheesecake chilled in the fridge, and it can be frozen for up to 3 months.
Notes
*Any plain crunchy cookie, even Oreos, can be substituted for graham crackers. Try gingersnaps during the holidays, or use an almond cookie to triple down on the almond flavor.