Preheat oven to 325° and ensure rack is set in the middle of the oven. Boil a kettle of water.
Heat milk and cream over low-medium heat until almost simmering. Split vanilla bean and scrape the soft interior with the tip of a knife. Add to milk mixture while heating.
Separate eggs. Refrigerate whites for another use. Combine yolks with ¼ cup sugar and whisk well.
When milk is just starting to bubble around the edges, gently pour a very small amount into the yolk mixture and whisk. Continue to add in small amounts, whisking continuously until well combined.
Place a dish cloth in the bottom of a large baking dish. Arrange 4 ramekins inside the dish so they aren't touching. Carefully pour custard evenly into the ramekins. You can strain the custard first if you prefer, however if you're using a real vanilla bean you may lose some of the seeds if the strainer is very fine.
Place the baking dish on the middle rack of the oven and pour boiling water into the dish, being careful not to get any water into the custards. Close the door and reduce the temperature to 300°.
Bake for 25-30 minutes. If you choose to make 6 smaller custards, baking time will be slightly reduced. They should jiggle slightly but not be liquidy.
Remove from oven and carefully remove ramekins to a rack. Once they are room temperature, cover with plastic wrap and refrigerate at least 4 hours or over night.
Right before serving combine white and brown sugar. Sprinkle about 1 Tbsp on each custard evenly. Torch the tops with a continuous movement until the sugar is melted and browning. Take care not to allow the sugar to burn. Or place custards under a preheated broiler on the top rack of the oven and watch carefully until tops are bubbling.
Let custards sit for a few minutes before serving to allow time for the sugar to harden.