Preheat your oven to 300°F (150°C) and prepare five 4-ounce jars in a baking dish.

In a saucepan, combine 1 cup of sugar and 1 teaspoon of water over medium heat, stirring until it becomes dark amber (5-8 minutes). Carefully add another teaspoon of water and divide the caramel into jars.

Whisk together the whole eggs and egg yolk until frothy (1-2 minutes) in a mixing bowl.

In a saucepan, heat 1 cup of whole milk and 1 cup of heavy cream with ¾ cup of sugar until dissolved (3-5 minutes), steaming but not boiling.

Gradually mix the warm milk into the egg mixture while whisking to prevent curdling; stir in 1 tablespoon of vanilla.

Strain the mixture through a fine-mesh sieve into a large measuring cup.

Pour boiling water into the baking dish around the jars until halfway up the sides, then place in the oven.

Bake for 30-35 minutes, checking for a slight jiggle in the center.

Let them cool for 15-20 minutes, then refrigerate for at least 3 hours.

Run a knife around the edge of each custard to release, invert onto a plate, and serve.