Combine Wet Ingredients: In a mixing bowl, stir together the milk, Greek yogurt, vanilla extract, and maple syrup until smooth.
Add Dry Ingredients: Add in oats, grated carrots, cinnamon, nutmeg, chia seeds, and raisins (if using). Stir until fully combined.
Mix in Extras (Optional): Fold in crushed pineapple, coconut, and chopped walnuts for added texture and flavor.
Portion and Refrigerate: Divide mixture into mason jars or sealable containers. Cover and refrigerate overnight (or at least 6-8 hours).
Serve and Enjoy!: In the morning, give it a stir. Add a splash of milk if needed. Enjoy cold or warm slightly in the microwave.