Heat the oil in a frying pan. Pat the chicken breasts dry and sear both sides for 2 minutes, remove, season with salt and let cool slightly.
Mix the cream cheese with about 1-2 tablespoons of cream until creamy, stir in the chopped tomatoes and basil, season with salt and pepper.
Spread the cream cheese mixture over the meat and place a slice of ham on top of each. Place a slice of ham on each of the puff pastry halves, place the chicken breasts with the cream cheese on top. Brush the edges of the puff pastry with egg white, fold the pastry around the chicken breasts, close tightly, fold down the edges if necessary. Brush the surface with egg yolk and prick several times with a fork.
Bake the filled puff pastry in the lower half of the 220 degree oven for 20-25 minutes until golden brown.