Ingredients
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
Preparation
Heat oven to 350. Butter six 5 1/2-inch gratin dishes (1 inch deep), and dust with sugar; arrange on a rimmed baking sheet. Toss rhubarb with 1/4 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.
Puree milk, cream, flour, eggs and yolk, remaining 1/2 cup sugar, 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.
