Stir in lemon juice, a small portion of brown sugar, and a pinch of cinnamon until the berries become slightly jammy and aromatic.

Remove the berry mixture from the heat and allow it to cool slightly while preparing the oats.

In a mixing bowl, combine rolled oats, milk, Greek yogurt, vanilla extract, chia seeds, remaining cinnamon, and salt.

Stir the mixture thoroughly until the oats are evenly coated and the ingredients form a thick, creamy base.

Spoon a layer of the berry mixture into the bottom of jars or containers.

Add the oat mixture on top of the berries, spreading it evenly so each jar has a balanced layer.

In a separate bowl, mix flour, melted butter, remaining brown sugar, and cinnamon until small crumbly clusters form.

Sprinkle the crumble mixture over the oat layer to create a lightly textured topping.

Cover the jars tightly and refrigerate overnight so the oats soften and absorb the liquid.

In the morning, stir gently if desired or enjoy layered with creamy oats, juicy berries, and crunchy crumble in every spoonful.