Prep your pan and oven: Heat the oven to 325°F (163°C). Line the bottom of a 9-inch springform pan with parchment and lightly mist the sides with nonstick spray.
Make the crust: In a bowl, combine graham crumbs, ground oats, brown sugar, melted light butter, and salt.
Add just enough water to create damp sand. Press firmly into the pan in an even layer. Bake for 8–10 minutes until lightly golden.
Cool while you prep the filling.
Soften and whisk: In a large mixing bowl, beat the cream cheese on medium speed until perfectly smooth with no lumps, about 2 minutes. Add Greek yogurt and mix until creamy.
Add dry and flavor: Beat in the sweetener, sugar, cornstarch, salt, vanilla, and lemon zest (if using). Mix on low until combined, scraping the bowl.
Avoid whipping in too much air.
Finish with eggs: Add the eggs one at a time, mixing on low just until incorporated. The batter should be silky and pourable.
Make the chocolate swirl: In a heatproof bowl, melt the dark chocolate and almond milk in 20–30 second bursts in the microwave, stirring until smooth. Stir in honey if you like a glossier finish.
Let it cool slightly so it’s warm but not hot.
Assemble: Pour the cheesecake batter over the cooled crust. Spoon the melted chocolate in 6–8 dots on top. Use a skewer or knife to gently swirl, making figure-eights without overmixing.
Bake low and slow: Place the pan on the center rack.
Bake 35–45 minutes, until the edges are set but the center wobbles like soft gelatin when you nudge the pan.
Cool gradually: Turn off the oven, crack the door, and let the cheesecake rest inside for 30 minutes. Move to a rack and cool to room temperature.
Chill completely: Cover and refrigerate at least 6 hours, preferably overnight. Release the springform ring, slice with a warm, dry knife, and serve.