01 - Preheat oven to 325°F. Line the bottom of a 9-inch springform pan with parchment paper and lightly grease the sides.
02 - In a mixing bowl, combine almond flour, powdered erythritol, melted butter, cinnamon, and salt. Stir until a crumbly, moist dough forms. Press the mixture firmly and evenly into the bottom of the prepared springform pan. Bake for 10 minutes, then remove and set aside to cool completely.
03 - In a small saucepan, combine chopped rhubarb, powdered erythritol, lemon juice, and water. Cook over medium heat, stirring frequently, until the rhubarb breaks down and the mixture thickens to a jam-like consistency, about 8 minutes. Remove from heat and let cool.
04 - In a large bowl, use an electric mixer to beat the softened cream cheese and powdered erythritol on medium speed until completely smooth and free of lumps. Add sour cream and blend well. Add eggs one at a time, mixing just until each is incorporated. Stir in vanilla extract and lemon zest. Do not overmix to avoid incorporating excess air.
05 - Pour the cheesecake filling over the cooled crust, spreading it into an even layer. Spoon small dollops of the cooled rhubarb compote across the surface. Use a butter knife or skewer to gently drag through the dollops, creating a decorative swirl pattern throughout the batter.
06 - Tap the springform pan firmly on the counter a few times to release trapped air bubbles. Place in the center of the oven and bake for 45 to 50 minutes, until the edges are set and the center has a slight jiggle. Turn off the oven, crack the door open, and allow the cheesecake to cool gradually inside the oven for 1 hour.
07 - Remove the cheesecake from the oven and transfer to the refrigerator. Chill for at least 2 hours, or until the cheesecake is fully set and firm. Slice into 12 portions and serve chilled.