• Using a hand mixer or stand mixer, beat butter and brown sugar for several minutes, until creamy. Add syrup and eggs and beat until combined, scraping the sides of the bowl as needed.
• In a separate bowl, combine flour, baking soda, and salt. Add flour mixture to the wet ingredients, and beat until just combined. Add oats and beat until combined. Stir in mix-ins (if using).
• Refrigerate the dough until firmed up and chilled, at least 2 hours (don't skip this step). Once chilled, scoop the dough into 1 1/2 tablespoon portions (I use a cookie scoop), then either freeze or bake immediately.

To freeze:

• Place dough balls into a freezer safe container, layering Reynolds Cookie Baking Sheets between the layers of dough. Make sure your dough balls are chilled and fairly firm. Don't layer soft dough balls or they'll lose their shape and stick together. Seal tightly and freeze for up to two months.

Bake:

• Preheat oven to 350°F and line cookie sheets with Reynolds Cookie Baking Sheets. Place the dough balls 2 inches apart on prepared baking sheets. Bake refrigerated dough for about 10 minutes and frozen dough for about 13 minutes, until the edges are just beginning to turn golden brown and the centers still look a bit underdone (they will continue baking as they cool). Place the baking sheet on a rack to cool completely.