Step 1: Preheat the oven
Preheat your oven to 350°F (175°C). Lightly grease your baking dish or line it with parchment paper.

Step 2: Prepare the crust
In a mixing bowl, cream together softened butter and sugar until light and fluffy. Add flour and salt, mixing until crumbly. Press the mixture firmly into the bottom of your prepared baking dish.

Step 3: Parbake the crust
Bake the crust for 15 minutes, or until lightly golden. Remove from the oven and set aside to cool slightly while you prepare the filling.

Step 4: Prepare the custard filling
In a large bowl, whisk the eggs, sugar, and flour until smooth. Gradually add cream and vanilla extract, whisking until fully combined.

Step 5: Add the rhubarb
Evenly scatter the chopped rhubarb over the warm crust.

Step 6: Pour the custard
Carefully pour the custard mixture over the rhubarb, making sure it spreads evenly across the pan.

Step 7: Bake
Return to the oven and bake for 40–45 minutes, or until the custard is set but still slightly jiggly in the center and the top is just beginning to turn golden.

Step 8: Cool and serve
Let the kuchen cool at room temperature for at least 30 minutes. Chill in the refrigerator before slicing for best texture.