Mix the base: In a medium bowl or measuring cup, whisk the milk, vanilla, maple syrup or honey, and a pinch of salt until smooth.
Add chia seeds: Sprinkle in the chia seeds and whisk well. Let sit for 2–3 minutes, then whisk again to prevent clumping.
Chill to set: Cover and refrigerate for at least 2 hours, ideally overnight, until thick and pudding-like.
Prep the berries: If using strawberries, hull and slice.
Toss mixed berries with lemon zest if you’re using it. If using frozen berries, thaw and drain excess liquid.
Layer the jars: Spoon a few tablespoons of chia pudding into the bottom of two small jars. Add a layer of berries.
Repeat layers until jars are full.
Add creaminess: Top with a dollop of yogurt if you like, or swirl it into the pudding for a softer texture.
Finish with crunch: Add a spoonful of nut butter or a sprinkle of chopped nuts or granola just before serving.
Taste and adjust: If you prefer sweeter, drizzle a little extra maple syrup on top.