Preheat your oven to 350°F (175°C). Spread the chopped pecans on a baking sheet and toast them for about 5–7 minutes until fragrant.
In a large mixing bowl, combine the softened butter, brown sugar, and granulated sugar. Cream together until light and fluffy.
Add in the egg and vanilla extract, mixing until fully combined.
In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add to the wet ingredients until just incorporated.
Fold in the cooled toasted pecans. Drop rounded portions of dough onto parchment-lined baking sheets.
Bake for about 10–12 minutes until edges are golden brown. Cool on baking sheet for five minutes before transferring to wire racks.
Prepare the glaze by mixing melted butter, brown sugar, milk, and powdered sugar until smooth, then drizzle over cooled cookies.