Place the oven rack in the center position and preheat to 375 degrees Fahrenheit. Line two baking sheets with parchment paper and set aside.
Whisk together 1 cup all-purpose flour, ¾ teaspoon salt, and ½ teaspoon baking soda in a medium bowl. Set aside.
Melt 4 tablespoons unsalted butter in an 8-inch skillet over medium-high heat, swirling to melt the butter evenly. Stir and cook for 2-3 minutes, scraping the bottom of the pan with a spatula until butter is golden brown and nutty in aroma.
Transfer the browned butter to a large bowl, making sure to scrape all of the browned bits from the bottom of the pan. Stir ½ teaspoon ground cinnamon into the butter.
Add ¾ cup packed dark brown sugar, ½ cup granulated sugar, and ½ cup vegetable oil to the browned butter and whisk until well combined.
Whisk in 1 large egg, 1 large egg yolk, and 1 teaspoon vanilla extract until smooth.
Mix the flour mixture into the browned butter mixture until fully combined.
Add 2 cups old-fashioned rolled oats, ½ cup semi-sweet chocolate chips, ¾ cup sweetened coconut flakes, and ½ cup chopped pecans. Stir into the cookie dough until well combined. The dough will be stiff in texture.
Scoop the dough into medium balls, about 3 tablespoons per scoop. Place them on the prepared baking sheets, leaving 2 inches between each cookie and limiting the number to 8 cookies per pan.
Use the bottom of a large measuring cup to press each dough ball into 2 ½-inch wide cookies. Reform the edges of the cookies into a circle as needed. If desired, press a few extra chocolate chips and chopped pecans into the top of the cookie dough.
Bake the cookies one baking sheet at a time for 8 to 10 minutes, until the edges are set and they are lightly browned on the surface. The centers should still be soft but not wet. Depending on your oven, you may want to rotate the baking sheet halfway through the baking time.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a cooking rack to finish cooling.