Baked Cod and Chorizo

Name: Baked Cod and Chorizo
Ingredients: 2 tablespoons olive oil; 4 ounces Spanish chorizo (cured sausage), thinly sliced; 1 pound Yukon gold potatoes, sliced 1/4 inch thick; 2 leeks (white and light green parts), cut into thin half-moons; ¼ teaspoon crumbled saffron threads; Kosher salt and black pepper; 1 1 1/2-pound piece cod fillet; ¼ cup fresh flat-leaf parsley, roughly chopped