Preheat the oven – set the oven rack to the center position and preheat to 375ºF (191ºC). Line two large baking sheets with parchment paper.

Mix the dry ingredients – In a medium bowl, whisk together flour, baking soda, and salt. Set it aside.

Make brown butter – Heat the butter in an 8-inch skillet over medium-high heat, swirling to melt evenly. Stir and cook, scraping the bottom of the pan with a spatula, until butter is golden brown and nutty in aroma, 1 to 2 minutes.

Make the dough – Transfer browned butter to a large bowl, scraping all of the bits from the pan. Stir in cinnamon. Add the brown sugar, granulated sugar, and oil. Whisk together until combined. Whisk in eggs, egg yolk, and vanilla until smooth. Use a spatula to fold the flour mixture into the butter mixture until combined.

Stir in oats and mix-ins – Stir in oats, coconut, chocolate chips, and pecans until well combined. The dough will be stiff in texture.

Portion the dough – Divide the dough into 3 tablespoons (2 ounces or 60 grams) sized pieces. Roll into a tight ball and place 2" apart, about 8 cookies per pan. Use the bottom of a measuring cup or ramekin to press each dough ball into 2 ½" wide cookies. Reform edges into a circle if needed.

Bake – Bake one sheet at a time. The edges should be set, lightly browned on the surface, and the centers soft but not wet, for about 8 to 10 minutes. Rotate halfway through baking.

Cool – Let the cookies sit for 5 minutes, and then transfer them to a wire rack. Cool completely before serving.