Milk Chocolate Cookies

1 cup all-purpose flour
1/2 cup unsweetened dutch-process cocoa powder
1/2 teaspoon baking soda
1/2 teaspoon salt
8 ounces good-quality milk chocolate, 4 ounces coarsely chopped, 4 ounces cut into 1/4-inch chunks
1 stick (8 tablespoons) unsalted butter
1 1/2 cups sugar
2 large eggs
1 teaspoon pure vanilla extract

Preheat oven to 325 F. Whisk together flour, cocoa powder, baking soda, and salt in a medium bowl and set aside.
Melt coarsely chopped chocolate with the butter in a small heatproof bowl set over a pan of simmering water. Transfer chocolate mixture to the bowl of an electric mixer fitted with the paddle attachment. Add sugar, eggs, and vanilla and mix on medium speed until combined. Reduce speed to low and gradually mix in flour mixture. Fold in chocolate chunks by hand with a rubber spatula. Chill the dough for a couple hours or overnight.
Scoop batter using a small ice cream scoop place them on a parchment lined baking sheet 2 inches apart and bake until cookies are flat and surfaces begin to crack, about 15 minutes. Transfer on parchment to wire racks. Let cool 5 minutes. Cookies can be stored in an airtight container at room temperature for up to 3 days.