Step 1

Preheat oven to 325°F. Combine rhubarb and 1/2 cup sugar in a mixing bowl. Add lemon juice and 1/4 teaspoon salt. Toss to coat the rhubarb evenly. Arrange in a single layer in a 2-quart baking dish. Tuck star anise and cinnamon stick into the dish. Cover with aluminum foil, and roast in preheated oven until rhubarb is tender when pierced with the tip of a knife, 20 to 25 minutes. Set aside, covered, to cool. The roasted rhubarb can be refrigerated up to 2 days.

Step 2

Spoon the ricotta into a food processor fitted with the chopping blade. Add egg, honey, vanilla, lemon zest, remaining 1/4 cup sugar, and remaining 1/4 teaspoon salt. Process until very smooth, about 1 minute.

Step 3

Lightly grease a 1-quart baking dish or a 9- to 10-inch pie plate. Scrape the ricotta mixture into the baking dish, and bake at 325°F until fragrant and toasty brown around the edges, about 1 hour. (The top may puff up as it bakes, but it will settle once out of the oven.) Let stand at room temperature at least 10 minutes. Serve warm, at room temperature, or chilled, topped with rhubarb mixture. The baked ricotta keeps, tightly covered, up to 2 days in the refrigerator.