This dessert couldn’t be simpler. Unlike many custards, it doesn’t require a hot-water bath. Shallow gratin dishes allow the rhubarb to spread out and cook evenly. You can also use 4-inch ramekins (2 inches deep). Simply give the rhubarb a stir halfway through step 1.
- Unsalted butter, for dishes
- 3/4 cup sugar, plus more for dishes
- 12 ounces rhubarb, trimmed and cut crosswise 1/4 inch thick
- 1 cup whole milk
- 1/2 cup heavy cream
- 1/3 cup all-purpose flour
- 2 large eggs, plus 1 large egg yolk
- Coarse salt
- Heat oven to 350°F. Butter six 5 1/2-inch gratin dishes (1 inch deep), and dust with sugar; arrange on a rimmed baking sheet. Toss rhubarb with ¼ cup sugar, and divide among dishes. Cover each first with parchment and then with foil, and bake until rhubarb is just beginning to release liquid and soften, about 30 minutes. Leave oven on.
- Purée remaining 1/2 cup sugar, milk, cream, flour, eggs and yolk, and 1/2 teaspoon salt in a blender until smooth. Divide mixture evenly among dishes. Bake, uncovered, until just set, 22 to 24 minutes. Let cool for 20 minutes.