Begin by setting your oven to 350°F (175°C). Prepare a baking sheet by covering it with parchment paper.

Caramelize the white chocolate: Spread the chopped white chocolate on a parchment-lined baking sheet. Bake for about 10 minutes, stirring halfway through, until it turns a golden caramel color. Once caramelized, set aside to cool.

Melt the chocolate and butter: In a heatproof bowl, melt the unsalted butter, semisweet chocolate, and bittersweet chocolate together over a simmering pot of water (double-boiler method) or microwave in short intervals. Stir until smooth. Let it cool slightly.

Mix wet ingredients: In a separate large bowl, whisk the eggs, granulated sugar, and light brown sugar until light and fluffy. Add the vanilla extract and mix.

Combine wet and dry ingredients: Gradually fold the melted chocolate mixture into the egg and sugar mixture. In a separate bowl, combine the flour, cocoa powder, baking powder, baking soda, and salt, whisking until well blended. Carefully incorporate the dry ingredients into the wet mixture, stirring until just combined.

Add caramelized white chocolate: Once the dough is mixed, fold in the caramelized white chocolate chunks.

Form cookies: Using a spoon or cookie scoop, portion the dough into 1.5-inch balls and place them on the prepared baking sheet, leaving about 2 inches between each.

Bake: Sprinkle each cookie dough ball with a small pinch of flaky sea salt. Place in the oven and bake for 10 to 12 minutes, ensuring the edges are firm while the centers remain a touch gooey.

After baking : let the cookies rest on the baking sheet for about 5 minutes. Then, move them to a wire rack to cool down completely. Relish these indulgent delights either warm or at room temperature.