Tomato and Gruyère Tart with Parmesan Spelt Pastry

This is really tasty. Unlike most of my other tart recipes, this one does not have a 'quiche' style filling. (NB photo pre-cooking!)

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   To make the pastry, blitz the flour and butter in a food processor until it resembles breadcrumbs. Stir in the Parmesan, then the egg yolk, with a little cold water if needed, until it just comes together to make a dough. Wrap in clingfilm, flatten slightly (to make it easier to roll out) and chill for 20 to 30 minutes.
   To make the filling, slice the pepper and onions. Heat the olive oil in a frying pan, then add the pepper and onions and cook for about 10 minutes until soft, stirring occasionally. Season.
   Heat the oven to 180C. Roll out the pastry to fit a shallow tart tin (about 23cm). Line with baking parchment and baking beans, and blind bake for 15 minutes, then remove the paper and beans and return to the oven for another 5 minutes.
   Thinly slice the olives and the tomatoes (or cut the cherry tomatoes in half).
   Allow the tart case to cool a little, then spread the mustard over the base and scatter over ¾ of the Gruyère.
   Add the onions and peppers, then lay the tomato slices on top and scatter on the olives, followed by the rest of the Gruyère. Add some more black pepper if you like, then bake at 180C for 20 minutes. Serve hot, warm or cold.