In a medium saucepan over medium heat, add the frozen blueberries and water. Cook for about 5 minutes until softened, then mash into a smooth puree, mixing in chia seeds and sweetener. Cool completely.

In a mixing bowl, combine rolled oats, almond flour, maple syrup, melted coconut oil, and a pinch of salt. Mix until crumbly, then press into an 8x8 baking dish lined with parchment. Freeze for 10-15 minutes to firm up.

In a blender, combine cream cheese, vanilla protein powder, Greek yogurt, sweetener, vanilla extract, and lemon juice. Blend until smooth and creamy.

Remove the crust from the freezer. Spread cheesecake filling evenly over it. Drop spoonfuls of blueberry swirl on top and gently swirl to create a marbled effect.

Cover with plastic wrap and refrigerate for at least 2-3 hours until set. Cut into squares or bars and serve cold.