Put margarine in a mixer and add slowly the flour.

Add salt, mustard, sugar and egg. When they turn into a maze, remove the mixture from the mixer and mold a ball.

Wrap with plastic film and leave in the fridge for 20-30 minutes. When out of the fridge leave 10' in room temperature.

Spread the margarine in the tart pan. Add pastry in the center and spread it everywhere.

With a pork make little holes in the surface of the pastry and bake in preheat oven in 180 oC for 20-25 minutes.

In a bowl mix the goat cheese with cream cheese.

When tart is baked, put the filling. Bake in 180 oC for 10 minutes.

Serve the tart hot with prosciutto slices on top.