In a medium saucepan over medium heat, melt the butter completely.

Turn off the heat and stir in the espresso grounds until well coated.

Cover and let steep for about 20 minutes.

Strain the mixture through a fine mesh strainer into a large bowl.

Discard the used espresso grounds; set the butter mixture aside.

In a medium bowl, whisk together flour, 1 tablespoon of espresso grounds, baking powder, baking soda, and kosher salt. Set aside.

In the bowl with the melted espresso butter, add brown sugar and granulated sugar, beating until light and fluffy (about 3 minutes).

Add eggs one at a time, mixing until fully combined.

Pour in vanilla extract and mix again.

Gradually add the dry flour mix, lowering the mixer speed to avoid a flour cloud until fully combined.

Add chocolate chunks or chips and mix until evenly distributed.

Cover the bowl and refrigerate the dough for at least 1 hour.

Preheat the oven to 350 degrees F (175 degrees C) and line baking sheets with parchment paper.

Using a medium cookie scoop, form balls of cookie dough and place 6 to 7 on each baking sheet with space to spread.

Bake for 7-10 minutes or until cookies are golden brown on the edges and soft in the center.

Sprinkle with flakes of salt after removing from the oven.

Place formed cookie dough balls on a baking sheet and freeze for about 20 minutes until firm.

Transfer to a freezer-safe bag for future use.