Preheat your oven to 350°F (175°C).
In a mixing bowl, cream together the softened butter and brown sugar until light and fluffy, about 3-4 minutes. Add the maple syrup and egg (or substitute), mixing until well incorporated.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix.
Cover the dough and chill it in the refrigerator for at least 30 minutes.
Use a cookie scoop or spoon to drop rounds of dough onto prepared baking sheets, spacing them about 2 inches apart.
Bake in your preheated oven for 10-12 minutes or until edges are golden.
Let the cookies cool on the baking sheet for a few minutes before transferring them to wire racks to cool completely.