Pre heat the oven to 195°C.
Place a small saucepan on a low heat and melt the butter. Add the flour and cook until glossy, stirring constantly. Slowly add the milk and half the blue cheese, whisk and warm the mixture until thickened. Season with generous amounts of sea salt and cracked black pepper.
Using a Large Saucepan cover potatoes with cold water and bring to the boil. Once boiling leave to cook for 2 minutes then tip the potatoes into a colander to drain and to cool.
Once cool enough to handle cut the potatoes in half and scoop a teaspoon of potato from the centre of each half of the potato.
Smash down the scooped potatoes mixture until there are no lumps, add the egg yolks and combine with the blue cheese sauce and set aside until later.
Place the potatoes into a hot roasting tray with the centre of the potato facing upward and roast for 30 minutes. After 30 minutes add a sprig of rosemary to each of the potatoes and return to oven until crisp and golden brown.
Place the potatoes on a shallow casserole dish before adding a teaspoon of Rosebud Sweet Onion Marmalade into to the whole of each potato scooped out earlier.
Top the potatoes with the blue cheese sauce mixture, followed by the remaining blue cheese and a good crack of black pepper to the top of each of the potatoes. Place in the oven and bake for further 15 minutes until golden brown.