Prepare the pan: Line the bottom of a 9-inch springform pan with parchment paper and lightly coat the sides with nonstick spray.
Preheat oven to 325°F (165°C).
Make the crust: In a bowl, mix almond flour, sweetener, melted light butter, vanilla, and salt until it resembles damp sand. Press into the bottom of the pan in an even layer. Bake for 8–10 minutes, until lightly golden.
Cool while you make the filling.
Cook the blueberry swirl: In a small saucepan, combine blueberries, water, sweetener, and lemon juice. Simmer over medium heat for 5–7 minutes, stirring and gently mashing some berries. If you want it thicker, stir in cornstarch with 1 teaspoon water and cook 1 minute more.
Cool slightly.
Mix the filling: In a large bowl, beat the light cream cheese with the sweetener on medium speed until smooth, about 1–2 minutes. Add Greek yogurt, vanilla, lemon zest, lemon juice, and salt. Beat on low until combined.
Add eggs and egg white one at a time on low speed, mixing just until blended. Do not overmix to avoid extra air.
Assemble: Pour the filling over the crust and smooth the top. Spoon small dollops of blueberry sauce over the batter and gently swirl with a skewer or knife. Don’t overwork it—2–3 passes create a pretty pattern.
Bake: Place the pan on the center rack and bake for 40–50 minutes.
The edges should look set, and the center should still have a slight wobble. Turn off the oven, crack the door, and let the cheesecake sit inside for 30 minutes to reduce cracking.
Cool and chill: Remove from the oven and let cool to room temperature. Run a thin knife around the pan edges. Cover and chill for at least 6 hours, or overnight, to fully set.
Serve: Release the springform ring.
Slice with a warm, dry knife for clean cuts. Garnish with fresh blueberries or a small spoon of extra sauce if you like.