In a large microwaveable mixing bowl, microwave cream uncovered for 3 minutes. Meanwhile, whisk together egg yolks, 1/4 cup sugar, and vanilla extract in a separate large mixing bowl until well combined. Whisking constantly, pour heated cream in a thin stream down the side of the bowl of egg mixture. Once combined, divide custard among four 1/2-cup ramekins (or any ovenproof or microwaveable container, like a mug). Place custards in a shallow microwaveable dish, making sure they don’t touch one another. Pour hot water between the ramekins until it reaches two-thirds of the way up the sides. Microwave until center of custards is just set, about 3 to 5 minutes. Remove from the microwave and let completely cool in the water. When cool, refrigerate covered for at least 1 hour. Once custards have rested, heat toaster oven to broil and, once heated, sprinkle about 4 teaspoons sugar on each custard. Place custards under broiler for about 5 minutes, or until the tops are caramelized and golden brown; watch carefully to avoid burning. Remove from oven and serve. (Alternatively, heat a conventional oven to high broil and arrange the rack in the upper third of the oven. Once the broiler is heated, sprinkle sugar on each custard and place under the broiler until tops are caramelized and golden brown, about 2 minutes; watch carefully to avoid burning.)