Whisk 3 tablespoons chia seeds, 1 cup milk, 1 tablespoon sweetener, and ½ teaspoon vanilla extract in a bowl vigorously for 2 full minutes until no clumps remain.
3 tablespoons chia seeds, 1 cup milk, 1 tablespoon sweetener, 0.5 teaspoon vanilla extract
Cover and refrigerate the mixture for 30 minutes. After 30 minutes, stir once to redistribute any seeds that settled to the bottom.
Blend half of the berries (½ cup) until smooth, leaving the other half whole for added texture. Optionally stir in 1 teaspoon lemon juice to the berries.
1 cup mixed berries, 1 teaspoon lemon juice
Spoon half of the chia pudding into serving jars or bowls, layer with pureed berries, then top with remaining pudding and the whole berries.
1 cup mixed berries
Cover and refrigerate for at least 3 hours and 30 minutes more (4 hours total minimum) until pudding is thick and fully gelled.