Cinnamon Breakfast Muffins

0 Preheat oven to 425°F. Line a muffin tin with muffin cups. Set aside.
1 First, make the cinnamon sugar swirl mixture in a microwave safe bowl, microwave the butter, sugar, cinnamon, and salt in 20 second increment, stirring between each. Repeat until the butter is fully melted. Transfer the mixture to a piping bag and set aside.
2 In a large bowl, combine the  brown sugar, eggs, melted butter, sour cream, and vanilla extract.
3 In a separate bowl, mix together the flour, cinnamon, baking powder, and salt.
4 Fold the dry ingredients into the wet, mixing only until combined.
5 Scoop batter into prepared muffin cups, filling just shy of the top of the cups. Snip the tip off the piping bag and make a swirl on top of your muffin or inject each muffin!
6 Bake for 5 minutes at 425F, then without opening the oven, turn the oven downto 350F and bake for an extra 15 minutes.