German Onion Tart (zwiebelkuchen)

To make the dough, combine butter, lard and flour in a bowl. Use your hands to rub in the butter and lard into the flour until it resembles fine breadcrumbs. Add water and salt, quickly knead until smooth. Roll out dough on a lightly floured bench. Grease a 24 cm round tart tin. Ease the pastry into the tin so it comes up the sides and press into corners. Trim pastry to top of tin and set aside in the fridge for 30 minutes.
To make the filling, preheat the oven to 190ºC. Cut onions in half and then in 3 mm slices. Fry the smoked speck in a non-stick pan over medium heat until lightly browned. Add onions, reduce heat to low and fry until softened and fragrant. Remove speck and onions from the pan and set aside to cool. Add cheese and mix well. Pour the onion and speck mixture onto the pastry.
Combine milk, cream, egg and flour in a bowl. Stir with a whisk to combine, then add salt, white pepper, nutmeg and paprika. Pour milk mixture over the onions and speck and bake for 40 minutes, or until cooked through.