Preheat the oven to 325 degrees F. Place the ramekins into a high-sided baking dish.
Heat the milk in a small pot over medium heat until warm but not hot.
Whisk together the eggs, yolks, salt, half the pumpkin pie spice, vanilla, and sugar. Slowly whisk the warm milk into the egg mixture. Pour the liquid into the ramekins and sprinkle the remaining pumpkin pie spice on top.
Place in the oven and pour hot tap water into the baking dish to about half way up the sides of the cups. Bake until the custard is set around the edges and just jiggles slightly in the middle, 35 to 40 minutes. Remove from the oven and let cool in the water bath. Refrigerate until chilled before serving, about 2 hours.