Prep the pan and oven: Heat the oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, leaving some overhang for easy lifting. Lightly grease the paper.

Melt the butter: Melt the butter in a microwave-safe bowl or on the stovetop. Let it cool for 3 to 4 minutes so it’s warm, not hot. This helps prevent scrambling the eggs.

Whisk the wet ingredients: In a large bowl, whisk the melted butter with the brown sugar and granulated sugar until smooth and glossy, about 30 seconds. Add the eggs and vanilla. Whisk until the mixture looks thick and slightly lighter in color.

Combine the dry ingredients: In a separate bowl, whisk the flour, salt, and baking powder to break up any clumps.

Stir it together: Add the dry mixture to the wet mixture and fold with a spatula until just combined. Don’t overmix.

Add the coconut: Fold in the shredded coconut until evenly distributed. If you’re using add-ins like chocolate chips or nuts, fold them in now.

Spread and smooth: Scrape the batter into the prepared pan. Smooth the top with a spatula. For a little sparkle and contrast, sprinkle a pinch of flaky sea salt on top.

Bake: Bake for 22 to 28 minutes, until the edges are golden brown and the center is set but still a touch soft. A toothpick should come out with a few moist crumbs, not wet batter.

Cool completely: Let the pan cool on a rack for at least 1 hour. Lift the bars out using the parchment, then slice into 12 to 16 squares. They firm up as they cool, which helps keep that chewy texture.