Preheat oven to 350°F. Prepare your mini muffin pan.
In a large mixing bowl, whisk together the Greek yogurt, eggs, melted butter, maple syrup, milk, and vanilla extract until smooth.
Add the flour, baking powder, baking soda, salt, and cinnamon. Stir just until combined. Do not overmix.
Fold in any desired mix-ins.
Divide the batter evenly among the mini muffin cups, filling each about ¾ full.
Bake for 10–12 minutes, or until the tops are lightly golden and a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring to a wire rack.