Brown the Butter:

• In a medium saucepan, melt the butter over medium heat. Continue to cook, stirring frequently, until the butter turns golden brown and has a nutty aroma. Be careful not to burn it!
• Remove from heat and let it cool for 5-10 minutes.

Mix the Sugars & Wet Ingredients:

• In a large mixing bowl, combine the browned butter, dark brown sugar, and granulated sugar. Beat until smooth.
• Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Combine the Dry Ingredients:

• In a separate bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon.

Mix Wet & Dry Ingredients:

• Gradually mix the dry ingredients into the wet mixture until just combined.
• Fold in the oats, dark chocolate chunks, and any optional mix-ins (nuts, raisins, or cranberries).
• Chill the Dough (Optional but Recommended):
• For extra chewy cookies, cover the dough and chill it in the refrigerator for at least 30 minutes (or up to 24 hours).

Bake:

• Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper.
• Scoop out dough balls (about 2 tablespoons each) and place them 2 inches apart on the baking sheet.
• Bake for 10-12 minutes, or until the edges are golden brown but the centers look slightly underbaked. They will set as they cool.

Cool & Enjoy:

Let cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.