Step 1

To make the cookies:

Step 2

Sift the flour, baking powder, cocoa, and salt together.

Step 3

Cream the butter in a medium bowl with an electric mixer at high speed until the butter is creamy, about 1 minute.

Step 4

Gradually beat in the granulated and brown sugars until the mixture is light in color and texture, about 3 minutes.

Step 5

Gradually stir in flour mixture to make a soft dough.

Step 6

Divide the dough into thirds. Wrap each portion of dough in wax paper to make a log about 5 1/2 inches long and 1½ inches in diameter. Twist the ends closed.

Step 7

Refrigerate until the dough is chilled and firm enough to cut and hold its shape, at least 2 hours and up to 2 days. (If the dough is chilled until it is very hard, let it stand to soften slightly or about 10 minutes before slicing, or the cookie slice could crack).

Step 8

Preheat the oven to 350F. Line two large baking sheets with parchment paper.

Step 9

Using a sharp knife, cut the dough rolls into ¼ inch thick rounds. Place them about 1 inch apart on the baking sheets.

Step 10

Bake the cookies for about 12 minutes until the edges of the cookies feel firm when lightly pressed. Let cool for 5 minutes on the baking sheet.

Step 11

Transfer to wire racks and let cool completely.

Step 12

To make the ganache:

Step 13

Bring the heavy cream to a simmer in a small saucepan over medium heat. Remove from the heat and stir in the earl grey tea. Let stand for 5 minutes. Strain the heavy cream mixture through a wire sieve into a bowl, pressing hard on the tea.

Step 14

Return the strained heavy cream to the saucepan and reheat to a simmer.

Step 15

Put the chocolate in a small bowl. Add the hot, heavy cream over the chocolate and let stand until the chocolate softens for about 3 minutes. Stir with a silicone spatula until the chocolate melts.

Step 16

Place the small bowl in a larger bowl of ice water and let stand, stirring and scraping the sides of the small bowl often with the spatula, until cooled and thickened to a spreadable consistency.

Step 17

Transfer the ganache to a pastry bag and pour on the flat side of the cookie a small amount of it, then cover the cream with another cookie, like a sandwich, flat sides together. Or omit the pastry bag and simply spread the cookie with about 2 teaspoons of the ganache. Repeat with the remaining cookies.

Step 18

Let stand until the ganache sets, about 1 hour.

Step 19

The cookies can be stored in an airtight container and refrigerated for up to 2 days. Let stand at room temperature for 30 minutes before serving.