2 ounces unsweetened chocolate
6 tablespoons (3 ounces) unsalted butter
1 cup granulated sugar
2 large eggs
1/2 teaspoon vanilla
1/2 teaspoon fine sea salt
1/2 cup all-purpose flour (2.25 ounces or 63 grams)
Preheat the oven to 350°F. Line an 8×8-inch pan with foil, leaving an overhang on all 4 sides. Spray with nonstick cooking spray.
In a large microwave-safe bowl, microwave the chocolate and butter on high in 30 second bursts, stirring between each burst, until the mixture is melted. Let cool slightly. Stir in the sugar. Mix in the eggs and vanilla. Stir in the salt and flour until combined. Pour into the prepared pan.
Bake for 20 minutes, or until a toothpick inserted in the center comes out with moist crumbs attached. Cool completely before cutting into squares.