In a large bowl, mix the flour, cocoa powder, sugar, and salt together. Add the butter and mix until crumbly. Stir in the egg yolks until the dough comes together. Press the dough into a tart pan and chill for 30 minutes.

Blind Bake the Crust

Preheat the oven to 350°F (175°C). Line the chilled crust with parchment paper and fill with pie weights or beans. Bake for 15 minutes, then remove the weights and bake for an additional 10 minutes until firm.

Chocolate Filling

Make the Chocolate Filling

In a saucepan, heat the cream and sugar until just boiling. Remove from heat and add the dark chocolate. Stir until melted and smooth. Allow to cool slightly, then whisk in the eggs and vanilla until fully combined.

Fill the Tart

Pour the chocolate filling into the baked tart shell and spread evenly. Bake for 20-25 minutes until the filling is set but still slightly wobbly in the center. Remove from the oven and let cool completely.

Raspberry Campari Sorbet

Make the Sorbet

In a saucepan, combine water and sugar, bring to a boil to dissolve. Remove from heat and add raspberries, Campari, and lemon juice. Blend until smooth and strain to remove seeds. Freeze in an ice cream maker according to manufacturer's instructions.

Assembly

Serve the Tart

Slice the cooled tart and serve with a scoop of raspberry Campari sorbet on the side. Garnish with cocoa nibs.