Preheat your oven to 325°F (165°C) and lightly grease a 6-inch springform pan or a large oven-safe ramekin.
Place the rolled oats into a blender or food processor and pulse until they reach a fine, flour-like consistency.
Press the ground oats firmly into the bottom of the prepared pan to create an even crust layer.
In a medium mixing bowl, whisk together the Greek yogurt, whole egg, liquid egg whites, maple syrup, vanilla extract, sea salt, and lemon zest until the batter is completely smooth and aerated.
Pour the yogurt mixture over the oat crust in the pan.
In a small bowl, mash the fresh raspberries with a fork until liquidy, then dollop the mash onto the top of the cheesecake batter.
Use a toothpick or the tip of a knife to gently swirl the raspberry mash into the batter for a marbled effect.
Bake for 35 to 40 minutes, or until the edges are firm and slightly golden while the center remains slightly jiggly.
Remove from the oven and let cool at room temperature for 30 minutes before transferring to the refrigerator to chill for at least 2 hours to fully set.