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, erythritol, melted butter, cinnamon, and salt. Stir until a crumbly, evenly moistened dough forms. Press the mixture firmly and evenly into the bottom of the prepared pan. Bake for 10 minutes, then remove and set aside to cool completely.
03 - In a small saucepan, combine chopped rhubarb, 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, beat the softened cream cheese and erythritol with an electric mixer until completely smooth and free of lumps. Add sour cream and blend briefly. Add eggs one at a time, mixing on low speed after each addition until just incorporated. Stir in vanilla extract and lemon zest. Do not overmix to avoid incorporating excess air.
05 - Pour the cream cheese filling over the cooled crust, spreading evenly. Drop small spoonfuls of the cooled rhubarb compote across the surface. Using a butter knife or skewer, gently drag through the compote dollops to create decorative swirls throughout the filling.
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 still has a slight jiggle. Turn off the oven, crack the door open, and let the cheesecake rest inside for 1 hour to cool gradually and prevent cracking.
07 - Remove the cheesecake from the oven and let it come to room temperature. Transfer to the refrigerator and chill for at least 2 hours, or until fully set. Slice into 12 even portions and serve chilled.