Cut the chicken fillets and bacon into 2cm pieces.
Cook the chicken and bacon in a little olive oil, then add the chicken bouillon, white wine and tarragon. Simmer until reduced by half.
Add the double cream, mustard, and mixed vegetables, seasoning with salt and pepper. Reduce further until creamy sauce is thick enough to coat the back of a spoon.
Transfer pie filling to an oven-proof dish. Lay out sheets of filo and slice in half, then lightly scrunch up and cover pie filling. Brush with melted butter.
Bake for 25 minutes, or until crispy and golden.