In a medium saucepan set over medium heat, melt the butter. Continue cooking, stirring often to prevent the bottom from burning, just until the butter starts to sizzle but does not brown, 2 to 3 minutes. Remove the pan from the heat, add the dried lavender, and let cool at room temperature for 30 minutes, stirring occasionally.
Preheat the oven to 350 F and set 2 racks at the upper-middle and lower-middle positions. Line 3 baking sheets (or as many as you have) with parchment paper or nonstick baking mats.
Strain the butter through a fine-mesh sieve into a large bowl, pressing down on the lavender with a spoon to extract all the butter, and discard the lavender. Add the brown butter and the granulated sugar to the butter and whisk to combine. Add the eggs and vanilla extract and whisk until ribbony and smooth, about 1 minute.
Add the flour, baking powder, baking soda, and salt and stir with a rubber spatula just until a dough forms. Mix in the chopped chocolate.
Using a large 2 1/3 inch (#16) cookie scoop or 1/4 cup measure, portion out the dough and roll into large balls. Place the dough balls at least 3 inches part on the prepared baking sheets (6 per sheet).
Bake 2 sheets at the same time, swapping the top sheet to the bottom rack and bottom sheet to the top midway through, until the tops of the cookies are lightly browned, 13 to 16 minutes, then bake the remaining sheet on either rack. (If reusing one of the baking sheets, allow it to cool for 15 minutes before baking another batch on it.). Let the cookies cool slightly on the baking sheets, then transfer onto a wire rack to cool completely.