Preheat the oven to 350°F (180°C) and prepare a muffin tin.
In a bowl, mix together the flour, chia seeds, baking powder, baking soda, and salt.
In a separate bowl, mix together the eggs, sugar or honey, milk, oil, and vanilla.
Pour the wet ingredients into the dry mixture and stir to combine.
If you like, add the fruit or chocolate chips.
Divide the batter evenly among the muffin cups.
Bake for 18–22 minutes until golden brown.
For special variations, try using Matcha powder, grated apple with cinnamon, or lemon zest with poppy seeds.