Whisk together the 2 3/4 cup all-purpose flour, 2 tablespoons Earl Grey tea leaves,1/2 teaspoon baking powder, and 1/4 teaspoon kosher salt in a bowl, and set aside.
In a food processor, blitz the 1 cup unsalted butter and 3/4 cup white sugar until smooth. Add the 1 large egg and 2 teaspoons grated orange zest and pulse to just combine.
Add the flour mixture and pulse to combine.
Transfer the mixture to a lightly floured surface and roll into two logs, about 2 inch in diameter.
Wrap the logs in plastic wrap, and chill for at least an hour.
Heat the oven to 350°F. Line cookie sheets with parchment paper, OR use a baking stone.
Slice the cookies 1/8 inch thick and place on the cookie sheet, spacing them about an inch apart.
Bake 14 to 16 minutes - the edges should lightly brown around the edges only (don't overbake!)
Remove from oven and let cool for 5 minutes then transfer to a rack to cool completely.