Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a large mixing bowl, combine the melted unsalted butter, granulated sugar, and brown sugar. Beat until light and fluffy, about 2 to 3 minutes.

Mix in one large egg and one teaspoon of vanilla extract until smooth, about a minute.

Gradually incorporate the all-purpose flour, cornstarch, baking soda, baking powder, and cinnamon. Stir until just combined.

Fold in the chopped pecans and optional toffee bits.

Cover the dough with plastic wrap and chill in the refrigerator for 30 to 45 minutes.

Use a medium cookie scoop to portion the dough into balls, about 1.5 inches in diameter. Optionally roll in granulated sugar.

Bake for 11 to 14 minutes until the edges are golden brown and centers are soft.

Let cool on the baking sheet for about 5 minutes before transferring to a wire rack.