Step 1Use the flat side of a knife to crack open the cardamom pods and remove the seeds. Set the seeds aside and discard the pods.
Step 2Place the half-and-half in a saucepan and bring to a simmer over medium-high heat. Add the cardamom seeds. Remove the saucepan from the heat and allow to steep 15 minutes. Return the saucepan to the heat and bring the mixture to a simmer.
Step 3In a mixing bowl, whisk the sugar into the yolks just until incorporated. Whisk a little hot half-and-half in with the yolk mixture until most of the liquid is incorporated and the egg mixture is quite warm. Pour the yolk mixture into the saucepan with the rest of the half-and-half and heat over low heat 1 to 2 minutes (be careful that it does not curdle). Strain the custard through a fine mesh sieve.
Step 4Heat the oven to 300 degrees.
Step 5Divide the custard among 8 (3-ounce) ramekins. Place the ramekins in a 13-by-9-inch baking dish at least 2 inches deep. Fill the dish with enough cool water to come 1 inch up the sides of the ramekins. Bake until the custard is set, 40 minutes. The center of each should be slightly wobbly; check by gently shaking the pan.
Step 6Remove the ramekins from the water bath and cool to room temperature. Refrigerate 4 hours or overnight before serving.