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 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 - Combine rhubarb, erythritol, lemon juice, and water in a small saucepan. Cook over medium heat, stirring frequently, until the rhubarb breaks down and the mixture reaches a jam-like consistency, about 8 minutes. Remove from heat and let cool.
04 - Using an electric mixer, beat the softened cream cheese and erythritol together on medium speed until completely smooth and free of lumps. Add sour cream, then incorporate the eggs one at a time, mixing briefly after each addition. Blend in the vanilla extract and lemon zest. Stop mixing as soon as everything is combined to avoid incorporating excess air.
05 - Pour the cream cheese filling over the cooled crust, spreading it into an even layer. Drop small spoonfuls of the rhubarb compote across the surface. Using a butter knife or offset spatula, gently drag through the compote dollops to create decorative swirls throughout the batter.
06 - Tap the springform pan firmly on the counter a few times to release trapped air bubbles. Place in the oven and bake for 45 to 50 minutes, until the edges are set and the center retains a slight jiggle. Turn off the oven, crack the door open, and allow the cheesecake to cool gradually inside for 1 hour.
07 - Transfer the cheesecake to the refrigerator and chill for a minimum of 2 hours, or until fully set and firm to the touch. Slice with a sharp knife dipped in hot water for clean portions.