Chocolate Marble Chunk Cookies

2 1/4 cups all-purpose flour
1 tsp baking soda
3/4 tsp salt
1 cup unsalted butter, softened
3/4 cup firmly packed light brown sugar
3/4 cup granulated sugar
2 tsp vanilla extract
2 large eggs
1/4 cup Dutch-processed cocoa powder, sifted
12 oz. bittersweet or semisweet bar chocolate, cut into 1/2-inch pieces
1 3/4 cups pecan pieces

Position a rack in the centre of the oven and preheat the oven to 375 F.

In a medium bowl, whisk together the flour, baking soda and salt. Set aside.

In the bowl of an electric mixer, using the paddle attachment, beat the butter and sugars at medium-high speed until light, about 2 minutes. Beat in the vanilla extract and eggs one at a time, mixing well after each addition and scraping down the sides of the bowl as necessary. At low speed, add the flour mixture, mixing just until blended.

Transfer 1 3/4 cups of the dough to another bowl and set aside. Add the cocoa powder to the dough remaining in the mixer bowl and mix on low speed until blended. Add half of the chocolate and half of the pecans and mix until blended. Stir the remaining chocolate and pecans into the light-coloured dough.

Fill one side of a 1-tablespoon measuring spoon with the light dough, making it well rounded, not level. Fill the remaining half with chocolate dough. Roll the doughs into a ball and place on an ungreased baking sheet. Moisten your palm to prevent sticking, and flatten the dough into a 1 1/2-inch disk. Repeat with the remaining dough, spacing the cookies 2 inches apart. Bake, one sheet at a time, for 8 to 10 minutes, until the lighter dough just begins to colour. Let the cookies cool on the baking sheets for 5 minutes, then transfer to a wire rack and cool completely. Makes about 60 cookies.

Store in an airtight container at room temperature for up to a week.

Source: The Good Cookie by Tish Boyle, 2002