Preheat the oven to 350 degrees.
In a mediumsaucepan over high heat, combine 3/4 c sugar with water.
Cook until golden brown, about 5 minutes.
Do not stir once sugar has dissolved.
Distribute hazelnuts among 6 ramekins.
Pour in caramelized sugar and allow to set.
In the top of a double boiler or in a microwave oven, heat half and half with chocolate just until the chocolate is melted.
In a medium mixing bowl beat eggs and egg yolks.
Add a small quantity of the chocolate mixture to warm the eggs.
Pour egg mixture back into chocolate mixture and whisk to blend.
Add remaining 1/2 c sugar and vanilla; mix well.
Divide custard among the ramekins.
Place ramekins in a baking dish and fill the dish halfway up the sides of the ramekins with hot water.
Place in oven and bake just until custard is set or until a knife inserted in the center comes out clean, about 45 minutes.
Remove from the water bath and cool slightly.
Refrigerate overnight.
Run a knife around the edges of the ramekins to loosen the custard; invert onto individual dessert plates.
Serve at once.