Preheat the oven to 350°F (177°C) and grease a 9×13-inch pan or line with parchment paper, leaving an overhang on the sides to lift the finished blondies out (makes cutting easier!). Set aside.

In a large bowl, whisk the flour, baking powder, and salt together.

In a medium bowl, whisk the melted butter and brown sugar together. Once completely combined, whisk in the whole egg, egg yolk, and vanilla extract until combined. Pour the wet ingredients into the dry ingredients and gently whisk until combined. Fold in the coconut and chocolate chips.

Evenly spread batter into prepared pan. Bake for about 35 minutes, or until a toothpick comes out *mostly* clean. Remove from the oven and allow the blondies to cool completely in the pan set on a wire rack before cutting.

Cover and store leftover blondies at room temperature or in the refrigerator for up to 1 week.