3 ounces bittersweet or unsweetened chocolate, chopped
9 tablespoons (126 g) unsalted butter, chopped
3/4 cup (105 g) basic gum-free gluten-free flour blend
3/4 cup (60 g) Dutch-processed cocoa powder (if you use natural cocoa powder instead, add 1/8 teaspoon baking soda to the recipe)
1/4 teaspoon kosher salt
1/2 cup (100 g) granulated sugar
3/4 cup (164 g) packed light brown sugar
2 eggs (1o0 g, weighed out of shell) at room temperature, beaten
1 tablespoon pure vanilla extract
2 tablespoons (2 fluid ounce) heavy cream, at room temperature
Preheat your oven to 350°F. Grease an 8-inch by 8-inch baking pan, line it with parchment paper that overhangs all 4 sides of the pan, and set it aside.
In a small, heat-safe bowl, place the chopped chocolate and butter, and place over a pan of simmering (not boiling) water. Stir occasionally until melted and smooth. Remove the bowl and set it aside to cool briefly. Alternatively, melt the chocolate and butter in the microwave in 30-second bursts on 80% power.
In a large bowl, place the flour blend, cocoa powder, salt, and granulated sugar, and whisk to combine well. Add the brown sugar, and whisk again to combine, breaking up any lumps. Add the eggs and vanilla, then the melted chocolate and butter mixture, and the heavy cream, and mix to combine. The batter should be thick but smooth. Scrape the batter into the prepared pan and spread into an even layer with a wet spatula.
Place the pan in the center of the preheated oven and bake just until firm to the touch and a toothpick inserted in the center comes out mostly clean (about 24 minutes). Allow to cool completely in the pan before lifting by the overhung parchment paper onto a cutting board. Slice into 9 or 16 squares.
Originally published on the blog in 2013. Video and most photos new, recipe unchanged (except for size of pan and baking time slightly), text mostly new.