Sweet and Smoky Onion and Mozzarella Tart

Making the caramelised onion bread yesterday has inspired me to appreciate the humble onion a little more in my cooking.  Although it takes a while for onions to soften to a wonderfully sweet goo, they do not require constant stirring so are pretty easy.   
Adding the smoked paprika gives this tart (oh it's a quiche, let's face it!) quite a subtle, sexy smoky edge which goes so well with the cool mozzarella.

This is using a 25cm fluted loose-bottomed flan tin

Ingredients 

For the Onions

4 Medium Onions, sliced thinly

2 Cloves of Garlic, minced

1 tspn Sweet Smoked Paprika (Pimenton)

2 tbsp Butter

Salt and Pepper

2 tspn Light Brown Sugar 

For the Pastry

200g Plain Flour (plus a bit extra for rolling)

100g Butter

1 tbsp Poppy Seeds (optional)

25g Mature Cheddar Cheese, grated

Salt

4-6 tbsp Milk

For the Filling

350ml Milk

2 Large Eggs

A handful of Fresh Chives

25g Mature Cheddar Cheese, grated

1 ball of Mozzarella

• For the onions, melt the butter in a pan and tip in the sliced onions, garlic, smoked paprika, brown sugar, salt and pepper.  Stir to combine then turn the heat to minimum and sizzle slowly for 40-45 minutes, stirring occasionally until soft, gooey and sweet.  Take off the heat and set aside.  
• Preheat the oven to 200C (fan) and thoroughly butter your flan tin.
• Meanwhile, to make the pastry put the flour into a bowl and add the butter.  I must admit here that I often use spreadable because I always have that in the fridge and it makes good pastry.  I have found that the most effective method using spreadable butter is to use a table knife to cut through the butter in the flour repeatedly until it is in very small pieces, you don't have to rub it in.  If you are using hard butter, grate it into the flour and cut through lightly with a knife.  At this point add the poppy seeds (if using), the cheddar cheese and a pinch of salt.  Then stir in enough of the milk to bring it into a ball of dough.
• Sprinkle your work surface with flour, put the ball of dough onto it then sprinkle that with flour and your rolling pin.  Roll the pastry out (moving it around after each roll to prevent sticking) until it is about 4-5mm thick and big enough to fit in your tin with overlap.  Roll the pastry onto your rolling pin then transfer onto the buttered tin.  Gradually work around the tin pushing the pastry into the edges carefully to avoid tearing it (patch any holes up with spare pastry), leave a bit of pastry overhanging the edges.
• Put foil or baking paper into the pastry case and weigh it down with baking beans or any dried pulses (I use lentils!).  Put it in the preheated oven to blind bake for 10 minutes, then remove the baking beans and foil/paper and put it back in the oven for 5 minutes.  Take it out of the oven and set aside, turn the oven down to 175C.
• In a measuring jug, measure the milk then add the eggs and beat with a fork.  Add the grated cheddar and snip in the chives, season with salt and pepper, stir to combine.
• Put the caramelised onions into the pastry case and spread out evenly.  Then pour over the egg mixture and tear pieces of mozzarella onto it.  I find this stage easier if I put the tart case into the oven on a baking sheet and pull the shelf out slightly, then pour in the filling and pop in the mozzarella.   
• Bake for 30-35 minutes until golden brown and set but with a bit of a wobble.  Trim the edges of the pastry then leave to cool for 15-20 minutes.  I think this is best eaten warm with a big salad.