Ingredients

3/4 cup sugar 

1/4 cup light corn syrup 

1/3 cup heavy cream, room temperature 

1 stick unsalted butter, room temperature, plus more for dish 

1 cup plus 2 tablespoons unbleached all-purpose flour 

1/2 teaspoon baking powder 

Kosher salt 

8 ounces bittersweet chocolate, finely chopped (1 1/2 cups), plus 2 ounces melted 

3 tablespoons vegetable oil 

1 cup granulated sugar 

1 cup packed light-brown sugar 

4 large eggs, room temperature 

1 1/2 teaspoons pure vanilla extract 

2 cups pecan halves (8 ounces) 

Flaky sea salt, such as Jacobsen, for sprinkling

Preparation

Caramel: Combine sugar and corn syrup in a saucepan. Cover and cook over medium-high heat until sugar has dissolved and mixture boils, about 5 minutes. Uncover and continue to cook, swirling pan occasionally and brushing down sides with a wet pastry brush, until mixture turns medium amber, 3 to 4 minutes more. Carefully add cream in a slow stream (mixture will bubble vigorously). Remove from heat and stir until smooth. Let cool until caramel thickens slightly but is still pourable, about 10 minutes. Makes 1 cup. Use immediately.

Brownies: Preheat oven to 350 degrees. Butter a 9-by-13-inch baking dish. Line bottom and long sides with parchment, leaving an overhang; butter parchment.

Whisk together flour, baking powder, and 3/4 teaspoon kosher salt. In a large heatproof bowl set over (not in) a pot of simmering water, melt chopped chocolate and butter with oil. Remove from heat. Add both sugars; whisk until smooth. Add eggs and vanilla; whisk until glossy, 1 minute. Add flour mixture; stir just until combined (do not overmix). Pour batter into prepared dish; smooth top with a spatula. Arrange pecans on top in a single layer.

Bake until a tester inserted into center comes out with moist crumbs, 40 to 45 minutes. Transfer dish to a wire rack; let cool completely.

Drizzle caramel over brownies; let cool until set, 30 minutes. Drizzle with melted chocolate; sprinkle with flaky salt. Let chocolate set (refrigerate for a few minutes, if desired), then cut into squares and serve.