In a large bowl, combine rolled oats, milk, Greek yogurt, honey or maple syrup, vanilla extract, and lemon zest. Stir until well mixed.

Fold in the fresh raspberries gently to avoid crushing them.

Divide the mixture evenly into mason jars or airtight containers.

Cover and refrigerate overnight (or at least 4 hours) to allow the oats to soak and soften.

In the morning, stir the oats and add additional milk if desired for a creamier texture.

Top with extra raspberries and a sprinkle of lemon zest before serving.