📖 Instructions

1. Get Started: Preheat your oven to 375°F (190°C). Lightly grease a 9-inch baking dish. This ensures the custard won't stick and will be easy to serve.
2. Make the Crumble Topping: In a medium mixing bowl, combine 1 cup all-purpose flour, 1/2 cup rolled oats, 1/2 cup packed brown sugar, and 1/4 teaspoon salt. Cut in 1/2 cup (1 stick) cold unsalted butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs. Set aside. (I like using my fingers, it feels more connected to the process).
3. Prepare the Rhubarb: In a separate bowl, toss 4 cups of chopped rhubarb with 1/4 cup granulated sugar and 1 tablespoon of cornstarch. This helps to thicken the rhubarb juices as it bakes, preventing a soggy bottom. Distribute the rhubarb evenly in the prepared baking dish.
4. Make the Custard: In a saucepan, whisk together 2 cups milk, 1/2 cup granulated sugar, 1/4 cup all-purpose flour, 2 large egg yolks, and 1 teaspoon vanilla extract. Cook over medium heat, stirring constantly, until the mixture thickens and comes to a simmer. This should take about 5-7 minutes. Make sure to whisk constantly to prevent lumps from forming! (Trust me, nobody wants lumpy custard!)
5. Assemble and Bake: Pour the custard evenly over the rhubarb in the baking dish. Sprinkle the crumble topping evenly over the custard. Bake for 30-35 minutes, or until the topping is golden brown and the custard is set. The topping should be a nice golden hue—that's how you know it's ready!
6. Cool and Serve: Let the dessert cool slightly before serving. This allows the custard to set a bit more and prevents burning your mouth. Serve warm, on its own or with a scoop of vanilla ice cream. If you're feeling fancy, a sprig of mint adds a nice touch!