In the bowl of a stand mixer with paddle attachment (recommended) or a large mixing bowl and wooden spoon; mix brown sugar and butter until light and fluffy.
Gradually add 3 ½ cups flour, mixing on low and building to medium speed (or using the brute strength of your stalwart arms) until combined. The dough will be sticky! It’s okay. (If you mix by hand you deserve an extra cookie.)
On a marble slab, large board, or big piece of parchment paper; sprinkle ½ cup flour to keep this sticky dough from sticking to everything.
Place dough on your working surface of choice and gently knead dough until the half cup of flour has been absorbed. Add additional flour, only as needed, to make a soft, pliable dough. You may not use all, or any, of the remaining ½ cup flour. Don’t overwork the dough. Stop as soon as it feels like playdough, soft but not sticky.
Divide dough in half, form into discs and wrap tightly in plastic wrap. Chill in refrigerator for 30 minutes.
Right before you remove dough from refrigerator, preheat oven to 325°Fdegrees, place rack on lower middle position. Line baking sheets with parchment paper or silicone mats and set aside.
Remove dough from fridge and place back on your lightly floured working surface.
Roll dough to between ¼ and ½ inch uniform thickness. I roll mine between two pieces of parchment.
Now you get to choose your shapes. Use holiday cookie cutters or cut into traditional shapes as detailed below .Use a fork to make designs or add holiday sprinkles as desired.
Place cookies two inches apart on baking sheets.
Bake for 15 – 20 minutes or until lightly golden. Adjust baking time as needed by size of your cookies.
Cool on wire rack before serving.
Repeat with remaining dough, keeping dough chilled until ready to use. All that butter gets soft quickly. It’s easier to work with when chilled.
Cookies keep for a week, sealed airtight at room temperature.