Toast the chopped pecans in 3 tablespoons of unsalted butter until fragrant.

Melt 8 ounces of unsalted butter until browned and set aside to cool.

In a bowl, combine 2.5 cups of all-purpose flour, 1 tablespoon of cornstarch, 0.75 teaspoon of salt, 0.5 teaspoon of ground cinnamon, and 1 teaspoon of baking soda.

In another bowl, mix 1 cup of dark brown sugar and 0.5 cup of granulated sugar with the browned butter.

Add 1 tablespoon of vanilla extract, 2 large eggs, and 1 egg yolk to the sugar mixture and mix until smooth.

Gradually add the dry ingredients to the wet ingredients and mix until combined.

Fold in the toasted pecans.

Scoop dough onto a baking sheet and top each cookie with a whole pecan half if desired.

Bake in a preheated oven at 350°F (175°C) for 10 minutes or until golden brown.

Allow to cool before serving.