1. In a medium saucepan over low heat, melt the unsweetened chocolate and butter, stirring until smooth. Remove from heat and let cool slightly.

2. In a separate bowl, whisk together granulated sugar, brown sugar, eggs, and vanilla extract until glossy and well combined.

3. Gradually whisk the melted chocolate mixture into the sugar-egg mixture.

4. Add flour and salt, and gently fold until just combined. Do not overmix.

5. Pour batter into a greased or parchment-lined 9×9-inch pan. Bake at 350°F (175°C) for 28–32 minutes, or until a toothpick inserted comes out with moist crumbs. Cool completely.

6. For the topping: In a saucepan over medium heat, stir together sweetened condensed milk, butter, and egg yolks. Cook until thickened (about 8–10 minutes), stirring constantly.

7. Remove from heat, stir in coconut and pecans.

8. Spread the warm topping over cooled brownies. Sprinkle with flaky sea salt if desired. Let set at room temp or chill for clean slices.