In a skillet, melt 3 tablespoons of unsalted butter over medium heat. Add 1 1/4 cups of finely chopped pecans, stirring frequently for about 5-7 minutes, until they are golden brown and fragrant. Pour the toasted pecans into a bowl and set aside to cool completely for later use in your Best Butter Pecan Cookies.

In a saucepan over medium-low heat, melt 2 sticks of unsalted butter. Continue cooking for about 6-8 minutes, stirring often, until the butter turns a rich amber color and releases a nutty aroma. Remove from heat and let it cool slightly while preparing the next ingredients.

In a medium bowl, whisk together 2 ½ cups of all-purpose flour, 2 tablespoons of cornstarch, 1 teaspoon of salt, 1 teaspoon of ground cinnamon, and 1 teaspoon of baking soda. Blend thoroughly for about 1 minute.

In a large mixing bowl, combine the slightly cooled browned butter with ¾ cup of dark brown sugar, ½ cup of granulated sugar, 2 teaspoons of vanilla extract, and 2 eggs at room temperature. Whisk together vigorously for about 2-3 minutes.

Slowly add the dry ingredient mixture to the wet ingredients, stirring gently with a spatula until just combined. Aim for a dough that is moist and slightly sticky but holds together well.

Gently fold the cooled, toasted pecans into the cookie dough, ensuring they are evenly distributed throughout the mixture.

Cover the mixing bowl tightly with plastic wrap or a lid and refrigerate the dough for 1-2 hours, or for up to 24 hours.

Preheat your oven to 375°F (190°C) and line two baking sheets with parchment paper. Scoop tablespoon-sized portions of dough onto the sheets, leaving space between each scoop. Bake in the preheated oven for 9-12 minutes.

Allow the cookies to cool on the baking sheets for about 5 minutes. Then, carefully transfer them to a wire rack to cool completely. Optionally, decorate the tops with additional pecan halves.