In a large, microwave-safe mixing bowl, melt the butter in the microwave for 1 minute until mostly melted with a few solid pieces remaining. Cool the butter in the fridge for about 15 minutes.

In another bowl, whisk together the flour, baking soda, and salt until well combined.

Remove the large mixing bowl from the fridge. Whisk the cooled melted butter with granulated sugar and light brown sugar until smooth.

Whisk in the egg, egg yolk, and vanilla extract until smooth and well combined.

Stir the dry ingredients into the wet ingredients until just combined. Gently fold in the old-fashioned oats and shredded coconut until just combined.

Cover the cookie dough and transfer it to the fridge to chill for 30 to 60 minutes while preheating the oven.

Preheat the oven to 375°F (190°C) for about 30 minutes.

Line a large baking sheet with parchment paper.

Using a medium cookie scoop (2 tablespoons, 30 ml), scoop the dough into balls and place them on the lined baking sheet about 3 inches (8 cm) apart.

Bake at 375°F (190°C) for 10 to 12 minutes, or until the edges are set and lightly golden brown.

As soon as the cookies come out of the oven, reshape them using a biscuit or cookie cutter slightly wider than the cookie.

Cool the cookies on the baking sheet for 5 minutes, then transfer them to a cooling rack to cool completely.