In a medium mixing bowl, combine the rolled oats, cocoa powder, chia seeds, and salt. Stir to mix well.
In a separate bowl or measuring cup, whisk together the milk, chocolate hazelnut spread, maple syrup (or honey), and vanilla extract until fully combined and smooth.
Pour the wet mixture over the dry ingredients and stir until all the oats are well coated and the mixture is homogeneous.
Divide the mixture into two jars or containers, sealing them tightly with lids.
Refrigerate the jars for at least 4 hours, preferably overnight, to allow the oats to soak and soften.
When ready to serve, give the oats a good stir. Top with chopped hazelnuts and sliced banana or berries for added flavor and presentation.
Notes
Serve in clear jars to showcase the layers; drizzle a little extra chocolate hazelnut spread on top for a gourmet touch!