Sift flour and salt into large bowl.

Add the butter, rub with fingertips until forms pea sized bits.

Add egg and 1 tablespoon of cold water.

Using a pastry blender mix until dough just starts to come together, adding more water a bit at a time as needed.

Press dough together and shape into a disk.

Wrap with plastic wrap and refrigerate for a least 30 minutes.

Keep refrigerated until rhubarb mixture is cooked down and caramelized.

Roll out pastry dough on lightly floured surface slightly larger than frying pan.

Cut rhubarb into 1-2 inch pieces

Put butter and sugar in a deep 10 inch frying pan with ovenproof handle.

Heat until the butter and sugar melt together.

Arrange rhubarb tightly on top, filling all gaps.

Cook over low heat for 20-30 minutes, or until caramelized (lightly browned) and excess liquid has evaporated.

Preheat oven to 375 degrees.

Cover rhubarb mixture with rolled out pastry dough.

Press down around the edge to enclose completely.

Bake 25-30 minutes until pastry is golden and cooked.

Remove from oven and let rest for 5 minutes.

Cover frying pan with serving plate and carefully flip over.

Serve with vanilla ice cream or whipping cream.