Butter individual ramekins and spread the jam equally in the bottom of each bowl. Set aside.
Prepare a bain-marie (deep tray half filled with water) and place in the oven.
Cream the butter and sugar until pale and fluffy. Beat the eggs in one at a time, beating well after each addition.
Stir in the mixed peel, flour, polenta, baking powder and milk. Mix well but do not beat.
Spoon the mixture into the ramekins on top of the jam, until they are three quarters full.
Place in the bain-marie. Cover the entire bain-marie with foil and place in the oven.
Cook the puddings for 50-60 mins or until a skewer inserted into the middle of the pudding comes out clean.
Remove from the oven and from the bain-marie. Uncover and allow to cool. To remove puddings from ramekins gently move knife around the outsides of the pudding. Invert onto a plate.
Limoncello Custard
Mix eggs and sugar until fluffy, then add cornflour.
Combine the milk and lemon, bring to gentle boil.
Slowly whisk the warm milk into the egg mixture, careful not to cook the eggs.
Cook mix over gentle heat until it thickens.
Strain and chill. Fold in whipped cream and limoncello to serve.