In a mixing bowl, beat together 1 cup plus 2 tablespoons of cold salted butter with ½ cup granulated sugar, ¼ cup light brown sugar, and 1 teaspoon vanilla extract until the mixture is light and fluffy, about 3-5 minutes.

Gradually mix in 1¾ cups all-purpose flour, ½ cup unsweetened shredded coconut, and ¾ teaspoon ground cinnamon until just combined.

Turn the dough out onto a clean surface and divide it into two equal logs. Roll each portion tightly in plastic wrap, shaping them into about 1½-inch diameter logs. Chill for at least 1½ hours.

Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

Once the dough has chilled, brush the surface of each log with a well-beaten egg, then roll them in additional shredded coconut. Slice the logs into ¼-inch thick rounds.

Arrange the sliced cookies on the prepared baking sheets, dipping the tops in sanding sugar. Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown.

Once baked, allow the cookies to cool on the baking sheets for a few minutes before transferring to a wire rack to cool completely.