Toast the walnuts (recommended): place the chopped walnuts in a dry skillet over medium heat and toast for 3–4 minutes, stirring frequently, until they smell nutty and develop tiny darker flecks. Remove to a plate to cool. Why: toasting blooms the nut oils and deepens flavor and crunch; adding them raw will taste milder.

Prepare the berry mix: put the mixed berries in a small bowl and add 1 tsp of the honey/maple syrup and a light pinch of salt; gently press a few raspberries with the back of a spoon to release some juice. Why: lightly macerating releases berry juices that ripple through the oats overnight, creating pockets of bright flavor rather than a flat, uniform sweetness.

Combine the wet ingredients: in a medium mixing bowl, whisk together the almond milk, chia seeds, remaining honey/maple syrup (about 1 2/3 tbsp left), and vanilla extract with the pinch of salt until the chia is distributed. Let the mixture sit 3–5 minutes, then whisk again to break up any chia clumps. Why: chia swell quickly and can form gelatinous clumps; an initial rest and re-whisk ensure an even texture.

Add the oats: stir the rolled oats into the chia-milk mixture until fully combined. The oats absorb liquid more evenly when stirred into a hydrated base. Why: adding oats after hydrating the chia allows you to control final texture—less stirring preserves whole oat texture, more stirring makes it creamier.

Fold in most of the berries and half the toasted walnuts: gently fold in about 3/4 of the berry mixture and half the toasted walnuts, reserving some berries and walnuts for topping. Why: folding most berries in lets their juices meld into the oats while keeping some fresh fruit for visual and textural contrast on top.

Portion and refrigerate: divide the oat mixture between two 12- to 16-ounce jars or containers, seal, and refrigerate for at least 6–8 hours (overnight is best). Why: chilling gives the oats time to soften and the chia seeds to thicken the mixture to a spoonable, pudding-like consistency.

Finish and serve: in the morning, give each jar a good stir. If the oats are too thick, loosen with a splash (1–2 tbsp) of almond milk. Top with the reserved fresh berries, the remaining toasted walnuts, and an extra drizzle of honey or maple syrup if you like. Why: stirring re-integrates any separated liquid and toppings add temperature contrast and crunch for a restaurant-quality finish.

Storage and reheating notes: keep sealed in the refrigerator for up to 3 days. Eat chilled or warm gently in the microwave for 20–30 seconds if you prefer warmth; add a splash more almond milk after heating to restore creaminess. Why: the texture changes slightly over time as oats continue to absorb liquid—adjust liquid before serving for best mouthfeel.