Rhubarb Royale

Preheat your oven to 375°F (190°C). Grease a 9-inch tart or pie dish with butter and set aside.

In a large mixing bowl, combine flour, baking powder, a pinch of salt, and sugar, then cut in cold butter using a pastry cutter or your fingertips until the mixture resembles coarse crumbs. Press the dough evenly into the bottom and up the sides of the prepared dish to form the pastry shell.

Trim and slice fresh rhubarb into half-inch pieces, then toss with sugar and a pinch of cinnamon. Spread the rhubarb mixture evenly over the unbaked pastry shell.

In a separate bowl, whisk together the egg, milk, a small amount of flour, and sugar until smooth to form the custard filling.

Pour the custard mixture evenly over the rhubarb layer in the pastry shell, ensuring the filling is distributed uniformly.

Bake in the preheated oven for 40 to 45 minutes, or until the custard is set and the pastry is golden brown at the edges. A knife inserted in the center should come out clean.

Remove from the oven and allow the Rhubarb Royale to cool on a wire rack before slicing. Serve warm or at room temperature.