Step 1: Preheat your oven to 325°F (160°C). Place four 6-ounce ramekins or oven-safe custard cups into a larger baking pan (a roasting pan works well).
Step 2: In a large bowl, gently whisk the eggs. Don't overwhisk; you want to combine them without creating too much foam.
Step 3: Gradually whisk in the granulated sugar until dissolved. Then, slowly whisk in the whole milk and vanilla extract until well combined.
Step 4: Carefully pour the custard mixture evenly into the prepared ramekins.
Step 5: Place the baking pan with the ramekins on the oven rack. Pour hot water into the larger baking pan, around the ramekins, until it reaches about halfway up the sides of the custard cups. This creates a water bath (bain-marie), which helps the custard cook evenly and prevents it from cracking.
Step 6: Bake for 50-60 minutes, or until the edges are set and a slight jiggle remains in the center when gently shaken. A knife inserted halfway between the center and edge should come out clean.
Step 7: Carefully remove the baking pan from the oven. Using tongs, remove the ramekins from the water bath and let them cool on a wire rack to room temperature. The custard will continue to set as it cools.
Step 8: Serve warm or chilled. Optionally, sprinkle with a pinch of ground nutmeg or cinnamon before serving.