Step 1

Preheat oven to 325 degrees. Place eight 4-ounce ramekins in a large roasting pan. Add 4 tablespoons water to a small pot. Add 1 cup sugar and stir to dissolve. Cook over medium-high, swirling occasionally, until caramel begins to turn amber, 6 to 8 minutes. Working quickly, divide caramel between ramekins, swirling ramekins to coat bottoms evenly, set aside.

Step 2

In a medium pot, heat milk over medium until hot, but not boiling. In a medium bowl whisk together whole eggs and yolks, salt, and remaining 1/2 cup sugar. While whisking, ladle some milk into the egg mixture. Whisk in remaining milk, one ladle at a time. Strain through a fine sieve into a large liquid measuring cup, and stir in vanilla. Divide custard evenly among ramekins.

Step 3

Transfer roasting pan to oven. Add enough boiling water to come halfway up the sides of the ramekins. Bake until custards are just set, about 35 minutes.

Step 4

With tongs, remove ramekins from hot water and let cool slightly. Cover and refrigerate until cold, at least 3 hours (or up to 3 days). To unmold, run a sharp knife around inside of each ramekins and invert onto a serving plate, gently shaking to release.