½ cup plus 3 tablespoons unsalted butter, at room temperature
⅔ cup granulated sugar
⅔ cup packed light brown sugar
1 teaspoon vanilla extract
1¼ cups unbleached all-purpose flour
⅔ cup old-fashioned rolled oats (not instant or quick cooking)
1 teaspoon baking soda
½ teaspoon kosher salt
9 ounces bittersweet chocolate (62-70 percent cacao), chopped into ½-inch pieces
1¼ cups pecan halves, toasted and chopped
1 cup sweetened shredded coconut
Using a stand mixer fitted with the paddle attachment, cream together the butter, granulated sugar, and brown sugar on medium speed for about 5 minutes, or until the mixture is light and fluffy. (This step wil take about 10 minutes if using a handheld mixer or spoon.) Stop the mixer a few times and use a rubber spatula to scrape the sides and bottom of the bowl and the paddle to release any clinging butter or sugar. Beat in the eggs and vanilla on medium speed for 2 to 3 minutes, or until thoroughly combined. Scrape the bowl and the paddle again to make sure the eggs are thoroughly incorporated.
In a medium bowl, stir together the flour, oats, baking soda and salt. Add the chocolate, pecans, and coconut and toss to combine. On low speed (or with the wooden spoon), slowly add the flour mixture to the butter mixture and then mix just until the flour mixture is totally incorporated and the dough is evenly mixed.
For the best results, scrape the dough into an airtight container and let it rest in the refrigerator overnight (or for at least 3 to 4 hours) before baking. When ready to bake, position a rack in the center of the oven, and heat the oven to 350ºF.
Drop the dough in ¼-cup balls onto a baking sheet, spacing them about 2 inches apart. Flatten each ball slightly with the palm of your hand.
Bake for 20 minutes, or until the cookies are golden brown on the edges and slightly soft in the center. Let the cookies cool on the baking sheet on a wire rack for 15 minutes, or until they are cool enough to remove with a spatula. Then transfer the cookies to a wire rack to cool completely, or enjoy them warm.
The cookies can be stored in an airtight container at room temperature for up to 2 days. The unbaked dough can be stored in an airtight container in the refrigerator for up to 1 week.