Preheat the oven to 350°F (175°C). Grease the muffin tin or line it with muffin liners.
In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, combine the melted butter, milk, eggs, orange zest, orange juice, and vanilla extract. Mix well until combined.
Pour the wet ingredients into the dry ingredients. Gently fold them together using a rubber spatula until just combined; do not overmix.
Carefully fold in the cranberries, ensuring they are evenly distributed throughout the batter.
Divide the batter evenly among the muffin cups, filling each about two-thirds full.
Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.
For a sweeter muffin, feel free to add a sprinkle of sugar on top of the batter before baking.
These muffins can be stored in an airtight container at room temperature for up to 3 days or in the freezer for up to 2 months.