Heat oven to 200C/180C fan/gas 6.
Heat the oil in a frying pan, then gently fry
the leeks until soft, about 5 mins. Cool.
Unroll the pastry onto a baking sheet.
Spread the soft cheese over the pastry
to within 3cm of the edges. Scatter over
the leeks, bacon and grated Emmental.
Flip the edges of the pastry over the
filling. Bake for 20 mins until golden.