Preheat your oven to 350ºF (180ºC). Butter a 9-inch (23cm) springform pan thoroughly. Dust the inside with flour or cocoa powder, ensuring even coverage, and tap out any excess. If you don’t have a glass-bottom springform pan, line the bottom with parchment paper for easy release.
In a small bowl, whisk together flour, cocoa powder, and baking powder. This mix will help distribute the leavening agent evenly throughout your batter, ensuring a uniform rise.
Set a large bowl over a saucepan of barely simmering water, creating a double boiler. In this bowl, combine chocolate and butter. Stir continuously until they melt together into a smooth, glossy mixture. Be careful not to get any water in the chocolate, as it can seize.
Remove the bowl from heat and stir in 2/3 cup (130g) of sugar. Next, add the egg yolks, vanilla extract, and chocolate extract (if using). Mix these until well combined.
Gradually add the dry mixture to the chocolate batter. Stir gently until it’s free of lumps, but do not overmix!
In a separate bowl, use a stand mixer fitted with a whip attachment or a hand whisk to beat the egg whites on medium-high speed. Whip until they just begin to hold their shape, then add a pinch of salt.
Gradually add the remaining 1/3 cup (70g) of sugar while continuing to whip until you achieve stiff peaks. The egg whites should be glossy and form a peak that holds its shape.
Gently fold one-third of the whipped egg whites into the chocolate mixture. This will lighten the batter, making it easier to incorporate the rest of the egg whites without losing volume. Keep folding until no streaks of white are visible.
Pour the batter into the prepared pan, smoothing the top. Now, strew the pieces of caramels over the top, but be cautious not to place them too close to the sides—they can stick and make serving difficult.
Bake for 25 minutes. The center should feel soft but almost set. Allow the cake to cool completely before removing the sides of the springform pan. This will help maintain its beautiful shape. Serve and enjoy the deliciousness!