Brown the butter: Melt butter in a small saucepan over medium, stirring often. When foam subsides and golden-brown bits form with a nutty aroma, remove from heat and pour into a medium heatproof bowl. Let cool about 10 minutes — it should be warm, not hot.

Mix dry ingredients: In a separate bowl, whisk oats, flour, salt, and cinnamon until evenly combined.

Dissolve the baking soda: Stir the baking soda into the teaspoon of boiling water until fully dissolved.

Combine wet ingredients: Whisk the warm browned butter with brown sugar, maple syrup, and vanilla until smooth. Whisk in the dissolved baking soda mixture.

Bring it together: Add the dry ingredients to the wet bowl and stir until just combined. Fold in shredded coconut and toasted pecans. Avoid overmixing.

Chill the dough: Portion the dough into 12 scoops (about 2 tablespoons / 40 g each). Place scoops on a parchment-lined tray, cover, and refrigerate for at least 1 hour or up to overnight.

Preheat the oven to 350°F (175°C). Line a baking sheet with parchment. Arrange chilled dough balls about 2 inches apart and press down slightly.

Bake for 8–10 minutes, until edges are golden and centers look slightly underbaked.

Let cookies cool on the pan for 5 minutes, then transfer to a wire rack to cool completely.