Remove the eggs from the fridge and leave them at room temperature for about an hour. Using eggs at the right temperature will allow them to create a frothy composition and increase threefold when battered.
Preheat the oven to 180°C/350°F/gas mark 4.
Slightly melt the extra 20 g of butter and grease the baking tray, base and walls.
Wash the rhubarb stacks, peel and cut into about 1 cm pieces. Mix with sugar and spices and leave aside.
Place the eggs, salt, orange zest, vanilla and sugar in a large bowl and beat with an electric mixer for 5-7 minutes. You will observe how the volume increases, the colour becomes lighter, and the batter gets a creamy consistency.
Add the melted and cooled butter and continue mixing with a spatula.
Sieve the flour, add the baking powder and place it over the above composition. Mix until it incorporates, but not for too long, or you risk flattening the batter.
Place the rhubarb together with the juice at the bottom of the tray, sprinkle some semolina and add the batter. The semolina will absorb some of the excess liquid, and the batter will absorb the rest of it, becoming soft and moist when baked.
Bake for 30-40minutes on the middle rack. When the time is up, check with a toothpick that the pie is ready.
Allow the pie to cool in the tray, place a fitting plate over and turn it upside-down.
You might need to slightly bang it to the table several times to ensure the entire pie unglues from the tray and remains nicely on the plate.
Cut in squares when completely cool.