Coffee Cake-Style Muffins

Preheat your oven to 180°C (about 350°F).
In a large bowl, mix together the flour, sugar, melted butter, eggs, milk, baking powder, salt, and vanilla extract until you obtain a smooth batter.
In a small bowl, mix the brown sugar and cinnamon to create the topping mixture.
Pour half of the muffin batter into greased and floured muffin cups.
Sprinkle the topping mixture generously over the muffin batter.
Cover with the remaining muffin batter.
Bake for approximately 18 to 20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool slightly before removing them from the muffin cups.
Enjoy your Coffee Cake-Style Muffins!