Add 3 tbsp chia seeds into a mixing bowl or jar.
Add 1 cup of milk of your choice.
Stir in sweetener and vanilla extract, if using.
Whisk everything thoroughly to avoid clumps.
Cover and refrigerate for 5 minutes; stir again to prevent settling.
Refrigerate for at least 2-4 hours or overnight until it thickens.
Add fresh fruits, nuts, or seeds on top and enjoy.