Preheat your oven to 400°F. Line a 12-cup muffin pan with paper liners (or grease the cups well).
Brown the butter: Melt the butter in a light-colored skillet over medium heat. Swirl occasionally. It will foam up, then subside. When amber specks form at the bottom and it smells nutty (3–4 minutes), remove from heat immediately. Pour into a small bowl and let cool slightly.
Mix dry ingredients: In a large bowl, whisk together flour, granulated sugar, brown sugar, baking powder, baking soda, and salt.
Mix wet ingredients: In a medium bowl, whisk together the cooled brown butter, buttermilk, eggs, and vanilla until smooth.
Combine: Pour wet mixture into dry mixture. Fold gently with a spatula until just combined — a few streaks of flour should remain. Do not overmix.
Fold in huckleberries: Sprinkle the flour-dusted huckleberries over the batter and fold with a few gentle strokes until evenly distributed. Batter will be thick.
Rest the batter: Cover the bowl and let it sit at room temperature for 20 minutes. This activates the leavening and gives taller, domed tops.
Fill the cups: Divide the batter evenly among the 12 cups, filling nearly to the top. Sprinkle generously with turbinado sugar.
Bake at 400°F for 18–22 minutes, until tops are deep golden and a toothpick inserted in the center comes out clean or with a few moist crumbs.
Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. Or enjoy one warm — no judgment.