Preheat oven to 425°F. Line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, garlic powder, sugar, black pepper, parsley, chives, and thyme.
Add the cold butter cubes. Use a pastry cutter or fingertips to work the butter into the flour mixture until uneven pea-sized and slightly larger butter pieces remain. Do not fully blend into fine crumbs.
If your kitchen is warm, refrigerate the bowl for 10 minutes before adding the buttermilk.
Pour in the cold buttermilk and gently stir just until the dough comes together. The dough should appear shaggy and slightly sticky.
Let the dough rest for 2 minutes to fully hydrate the flour.
Turn the dough onto a lightly floured surface. Gently press into a rectangle about 1 inch thick.
Fold the dough in thirds like a letter. Rotate and gently flatten again. Repeat this process 2 more times to create flaky layers.
Pat the dough to about 1-inch thickness. Cut biscuits using a sharp biscuit cutter, pressing straight down without twisting.
Gather scraps gently if needed, avoiding repeated rerolling.
Arrange biscuits on the prepared baking sheet with edges barely touching or about ¼ inch apart.
Brush tops lightly with buttermilk.
Optional but recommended: freeze biscuits for 10 minutes before baking for maximum flakiness.
Bake for 18–20 minutes or until tall and deeply golden brown.
While biscuits bake, melt the butter over low heat. Add garlic and cook for about 20–30 seconds until fragrant and softened but not browned. Stir in parsley and salt.
Lightly brush warm biscuits with garlic herb butter immediately after baking.
Sprinkle lightly with flaky sea salt if desired and serve warm.