In a large mixing bowl, combine rolled oats, milk, Greek yogurt, chia seeds, peanut butter, maple syrup, vanilla extract, and a pinch of salt. Stir well until thoroughly mixed.

Cover the bowl and refrigerate for at least 3 hours, ideally overnight.

Once chilled, stir the mixture again, adding a splash of milk if too thick and adjusting sweetness if desired.

In mason jars, layer the oat mixture followed by a layer of jam. Repeat layers until jars are filled.

Finish with a dollop of additional jam and garnish with fresh berries and chopped peanuts if desired.