Melt ½ cup unsalted butter with 2 tablespoons Earl Grey tea leaves in a saucepan or microwave in 15-second intervals; let cool completely.
In a large bowl, mix the melted butter with ½ cup granulated sugar and ¼ cup light or dark brown sugar until combined.
Add 1 ½ cups all-purpose flour, ½ teaspoon baking powder, ½ teaspoon baking soda, and ½ teaspoon salt; mix until no dry spots remain.
Cover and refrigerate the dough for 30–60 minutes or up to 2 days.
Preheat the oven to 325°F/163°C and line two baking trays with parchment paper.
Place 4 tablespoons granulated sugar in a small bowl.
Scoop 2–3 tablespoons of dough, roll in sugar, and place on trays 3–4 inches apart.
Scoop 2–3 tablespoons of dough, roll in sugar, and place on trays 3–4 inches apart.
Bake 9–11 minutes until edges are golden and set.
Cool on the pan for 5 minutes, then transfer to a wire rack.
For rounder cookies, swirl a circular cutter or mug around the warm cookies.