Combine melted, cooled butter and sugars in a large bowl and stir until well-combined.

Add egg and vanilla extract and stir well.

In a separate, medium-sized bowl, whisk together flour, baking soda, baking powder, and salt.

Gradually add flour mixture to wet ingredients, stirring until completely combined, then stir in chocolate chips.

Cover bowl tightly with plastic wrap and transfer to the refrigerator to chill for at least 30 minutes and up to 5 days.

Once dough has chilled, preheat oven to 350F (175C) and line a baking sheet with parchment paper. Set aside.

Scoop dough by rounded 1 ½ teaspoon-sized scoop onto prepared cookie sheets, placing at least 1″ apart.  I like to roll my cookies between my palms into balls after scooping them so that they bake very uniform and round, but this is not necessary.

Bake on 350F (175C) for 6-8 minutes — cookies may still seem slightly soft in the centers, that is OK, they will cook completely on the cookie sheets. Don’t over-bake or your cookies will be too hard.

Allow to cool completely on cookie sheets.