Preheat the oven to 200°C/gas mark 6. Wrap the beetroots individually in foil, drizzle with the oil and roast for 1 hour or until tender when a skewer is inserted.
Meanwhile, combine the ingredients for the horseradish and lemon crème fraîche and season to taste. Set aside in the fridge to allow the flavours to develop.
Melt the 15g of butter and brush this around the inside of 6 individual ramekins. Tip the breadcrumbs into each and tilt so the bottom and sides are coated.
Once the beetroots are roasted, leave to cool for 10 minutes then remove the skins. Place the beetroots in a blender and blend until smooth.
Turn the oven up to 220°C/gas mark 8 and place a baking sheet in it on the bottom third of the oven.
Melt the 30g butter in a small saucepan, then add the flour and cook for 1 minute. Remove from the heat and add a splash of milk, then stir. Continue to add the milk very gradually to prevent lumps from forming then put back on the heat, bring to the boil and cook for 2 minutes. Pour this into a large bowl and leave to cool slightly before adding the pureed beetroot and the egg yolks. Season to taste.
Whisk the egg whites to medium/stiff peaks. Stir a third of the egg whites through the beetroot mixture using a large metal spoon to loosen it, then add the remaining egg whites. Fold these through very carefully to keep as much volume as possible.
Carefully transfer this mixture to the prepared ramekins and place on the preheated baking tray. Cook for 35-40 minutes then serve with the horseradish and lemon crème fraîche.