Make the Buttered Pecans:

• Melt the 3 tablespoons of butter in a large skillet over medium heat.
• Add the finely chopped pecans to the melted butter.
• Cook, stirring occasionally, for 4-5 minutes, or until the pecans are lightly toasted and fragrant. Be careful not to burn them.
• Remove from heat and set aside to cool.

2. Make the Cookie Dough:

• Combine Dry Ingredients: In a large bowl, whisk together the all-purpose flour, cornstarch, salt, cinnamon, and baking soda until well combined. Set aside.
• Brown the Butter: In a small, light-colored saucepan (a light-colored pan makes it easier to see the browning) over medium heat, melt the 2 sticks (8 ounces) of butter. Continue to cook the butter, swirling the pan occasionally, until it turns a rich amber color and has a nutty aroma. You will see small browned bits form at the bottom of the pan. This is what gives the butter its browned flavor. Watch carefully to prevent burning. Once browned, remove from heat immediately.
• Combine Sugars and Browned Butter: Pour the browned butter (including the browned bits) into a large mixing bowl. Add the packed dark brown sugar and granulated sugar. Whisk well to combine.
• Add Wet Ingredients: Add the vanilla extract to the butter and sugar mixture. Beat in the eggs and egg yolk, one at a time, beating until just combined after each addition. Do not overmix.
• Combine Wet and Dry Ingredients: Gradually add the dry ingredients (flour mixture) to the wet ingredients, mixing with a rubber spatula or wooden spoon until just combined. Do not overmix.
• Fold in Buttered Pecans: Fold in the cooled buttered pecans until evenly distributed.
• Chill Dough: Cover the bowl with plastic wrap and refrigerate for at least 4 hours, or preferably overnight. Chilling the dough allows the flavors to meld and prevents the cookies from spreading too much during baking.

3. Bake the Cookies:

• Preheat Oven and Prepare Baking Sheets: Preheat your oven to 375°F (190°C). Line two large baking sheets with parchment paper.
• Scoop Dough: Using a large cookie scoop (about 3 tablespoons) or a spoon, scoop out rounded portions of the chilled cookie dough.
• Arrange on Baking Sheets: Place the dough balls onto the prepared baking sheets, leaving about 3 inches of space between each cookie to allow for spreading.
• Add Pecan Halves (Optional): If desired, gently press a pecan half into the top of each cookie dough ball.
• Bake: Bake one tray at a time for 10-11 minutes, or until the edges are golden brown and the centers are still slightly soft.
• Shape Cookies (Optional): If any edges of the cookies spread out too much during baking, you can use a spatula or the back of a spoon to gently press them back into shape immediately after removing the cookies from the oven.
• Sprinkle with Sugar (Optional): Sprinkle the warm cookies with granulated sugar, if desired.
• Cool: Let the cookies cool on the baking sheets for 15 minutes before carefully transferring them to a wire rack to cool completely.