Preheat your oven to 350°F (175°C). Prepare your cake pan by greasing it lightly and lining the bottom with parchment paper.
In a double boiler or microwave, melt the cubed butter and chopped chocolate together until smooth. Stir occasionally to combine. Let it cool slightly.
In a separate bowl, whisk together the flour, cocoa powder, baking powder, and a pinch of salt. Set aside.
In a large mixing bowl, beat the egg yolks with 2/3 cup of sugar until the mixture becomes pale and thick. Add the melted chocolate mixture, vanilla extract, and chocolate extract (if using). Mix until smooth.
Gradually add the dry ingredients to the chocolate mixture, folding gently with a spatula until just combined.
In a clean bowl, whip the egg whites until soft peaks form. Gradually add the remaining 1/3 cup of sugar and continue beating until stiff peaks form.
Carefully fold the whipped egg whites into the chocolate batter in three additions, ensuring not to deflate the mixture.
Pour half of the batter into the prepared cake pan. Evenly space the halved caramels over the batter, then pour the remaining batter on top, spreading it evenly.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Don’t overbake!
Allow the cake to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely. Serve as is, or with a drizzle of warm caramel sauce or a dollop of whipped cream for extra indulgence.
