Crème brûlée may seem like a super fancy dessert, but it is actually one of the easiest desserts to make - especially when you make it in a slow cooker.
Whisk together yolks, 1/4 cup sugar, salt, and vanilla in a bowl, then gently whisk in cream. Strain mixture into a liquid measuring cup.
Line bottom of a 6-quart oval slow cooker with a folded kitchen towel to create a level surface so ramekins won't slide around. Set 4 (4-ounce) ramekins on towel. Fill slow cooker with enough water to come halfway up sides of ramekins.
Pour custard evenly into ramekins. Drape paper towels over top of slow cooker (to absorb any condensation during baking), then cover with lid. Cook on Low until custard is set but jiggles slightly, about 2 hours.
Transfer ramekins to a rack to cool completely, about 45 minutes. Chill custards, uncovered, until cold, at least 3 hours.
Sprinkle 1 teaspoon sugar evenly over each ramekin. Brûlée sugar with a culinary torch and serve immediately.