Step 1Combine the half-and-half and whipping cream in a small saucepan. Split the vanilla bean in half lengthwise. With the tip of a knife, scrape the tiny seeds along the inside of the vanilla bean into the cream. Add the pod halves. Whisk a few times and heat to a simmer. Turn off heat and let stand 10 minutes to steep before removing the pod.
Step 2Combine the sugar and cornstarch and whisk into the cream. Heat to a boil, stirring occasionally. Simmer 1 minute. Quickly whisk the egg yolks into the cream mixture, then remove the mixture from the heat and strain. Cover and let the creme anglaise stand while preparing the quince.
Step 3Heat the oven to 375 degrees.
Step 4Place the quince in a small pan. Bake until tender, 1 hour, turning the quince during roasting to prevent any burned spots. Remove from the oven, cut into quarters and remove the seeds.
Step 5Meanwhile, heat the broiler. Place the quince on a shallow tray or baking pan, drizzle with the butter, then sprinkle with the sugar. Broil until the sugar melts and the wedges begin to brown around the edges, 3 to 4 minutes. Grate a little fresh nutmeg over the top. Arrange 4 pieces of quince on each plate. Garnish with more grated nutmeg and drizzle with the creme anglaise.