• Gather all ingredients and equipment before starting so preparation proceeds smoothly.

For the Chocolate Crust:

• Combine the chilled butter, flour, cocoa and salt in a food processor and pulse until the mixture looks like fine crumbs. If you don't have a processor, use a pastry cutter or two forks to cut the butter into the dry ingredients.
• Add the cold water and pulse briefly until the dough just comes together into a ball, adding up to 1 tablespoon more water if required. Wrap the dough tightly and refrigerate for 1 hour to firm up.

For the Chocolate-Caramel Filling:

• Place the sugar and 1/4 cup water in a medium saucepan and heat over medium without stirring. Allow the syrup to simmer and watch it carefully until it turns a deep golden-amber color, about 6–10 minutes.
• Remove the pan from heat and whisk in the butter and heavy cream until fully incorporated. Add the chocolate chips, vanilla, and a pinch of salt; let the mixture sit for about a minute, then whisk until the filling is completely smooth. Cover and let cool to room temperature.

For the Raspberry Sauce:

• Combine the raspberries and 1/2 cup sugar in a small saucepan and bring to a gentle simmer over medium heat. Add 2 tablespoons of water if the fruit seems dry and simmer for 5–6 minutes until softened.
• Push the cooked raspberries through a fine-mesh strainer into a bowl, using the back of a spoon to extract the puree and leaving the seeds behind. Set aside the sauce, reserving roughly one-third for serving.

Baking and Assembly:

• Preheat the oven to 350°F (177°C). On a lightly floured surface, roll the chilled dough out to be about 1 inch larger than your tart pan (works with 8–10 inch pans). Gently ease the dough into the pan, trim excess, and prick the bottom with a fork to prevent bubbling.
• Line the crust with a round of parchment and fill with pie weights or dried beans. Blind-bake for 15 minutes, remove the weights and paper, then bake an additional 10 minutes until the crust is crisp and well-browned. Allow it to cool, then carefully remove from the pan and transfer to a serving platter.
• Spread the cooled chocolate-caramel filling evenly into the baked crust, taking it to the edges. Spoon a thin layer of the raspberry sauce over the filling, keeping about one-third of the sauce for serving.
• Arrange the fresh raspberries on top of the tart, pressing them gently into the sauce so they sit snugly. Refrigerate until the tart firms, and remove about 30 minutes before serving. Serve slices with the reserved raspberry sauce.