A moist and fluffy chocolate chunk muffin loaded with chocolate chips and a hint of cinnamon.
Melt the butter and set aside to cool to room temperature. Preheat the oven to 375° and have ready a greased muffin tin lined with cupcake liners.
Add flour, baking soda, baking powder, sea salt, and cinnamon (if using) to a medium-sized mixing bowl. Whisk to combine and set aside until ready to use.
Add buttermilk, eggs, granulated sugar, brown sugar, and vanilla extract to a large mixing bowl. Whisk until well-combined. Slowly, drizzle in the cooled butter and whisk to combine. Add the dry ingredients, and gently stir with a wooden spoon until fully mixed. Stir in the chocolate chunks. Do not overmix.
Fill the muffin liners almost all the way to the top, and bake for 22-25 minutes, or until the tops of the muffins are golden brown. Allow to cool on a wire rack for 10 minutes. Serve and enjoy.
Do not combine wet ingredients until the butter has cooled to room temperature.
Consider using parchment paper muffin liners. If you don't have this kind, it's best to spray the muffin liners and the pan with cooking spray before adding the batter.