Mini Chicken Potpies

skin-on, bone-in chicken thighs (about 6)

Kosher salt and freshly ground pepper

extra-virgin olive oil

leeks (white and light green parts only), sliced 1/4 inch thick

fennel bulb, cored and thinly sliced, plus 1 tablespoon chopped fronds

all-purpose flour, plus more for dusting

Pernod or white wine

saffron (optional)

heavy cream

finely grated orange zest

medium red-skinned potatoes (about 1/2 pound), diced

small plum tomatoes, finely chopped

box frozen puff pastry, thawed

large egg, lightly beaten