Cinnamon Sugar Swirl Muffins

Preheat your oven to 375°F (190°C). Line a muffin tin with paper liners or grease it lightly with butter or cooking spray.
Mix the Dry Ingredients:

In a large bowl, whisk together the flour, granulated sugar, brown sugar, baking powder, salt, cinnamon, and nutmeg.
Combine the Wet Ingredients:

In another bowl, whisk together the melted butter, milk, eggs, and vanilla extract.
Combine Wet and Dry Ingredients:

Gradually add the wet ingredients to the dry ingredients, stirring until just combined. Do not overmix, as this can make the muffins dense.
Prepare the Cinnamon Sugar Swirl:

In a small bowl, combine the brown sugar, granulated sugar, and cinnamon for the swirl.
Fill the Muffin Cups:

Spoon a small amount of the muffin batter into each muffin cup, just enough to cover the bottom. Then, sprinkle a generous amount of the cinnamon sugar mixture over the batter. Add another spoonful of batter on top, and finish by sprinkling the remaining cinnamon sugar over the top of each muffin.
Swirl the Cinnamon Sugar:

Use a toothpick or skewer to swirl the cinnamon sugar into the batter, creating a marbled effect.
Bake the Muffins:

Bake for 18-22 minutes or until a toothpick inserted into the center comes out clean. If the muffins start to brown too quickly, cover them loosely with aluminum foil for the last few minutes of baking.
Cool and Serve:

Let the muffins cool in the tin for about 5 minutes, then transfer them to a wire rack to cool completely. Serve warm or at room temperature.
Serving and Storage Tips