1. For the gnocchi: cook the potatoes, whole and unpeeled, in about 2-3 inches of water. Once cooked, peel and mash them well or put through a potato ricer.
2. Mix in the flour, grated Kerrygold Aged Cheddar and egg yolks into the potatoes, season with sea salt and freshly ground black pepper. Tip the dough onto a lightly floured surface and knead lightly until well combined. Shape into three or four balls.
3. Dust the surface with more flour if necessary. Using your fingertips, roll the dough into a sausage about ¾-inch in diameter. Cut the dough into 1-inch pieces, then roll the gnocchi against the front of a fork to create ridges. (This will help hold the sauce on the gnocchi once cooked.)
4. Meanwhile bring a large saucepan of salted water to the boil and add the gnocchi. When they have risen to the surface of the water they are cooked, so remove quickly and drain.
5. For the sauce place a frying pan over a medium heat and add the butter, when the butter has melted add the sage and cook until it is slightly crispy
6. Tip the gnocchi into a frying pan and mix them gently in sage butter sauce. Transfer to serving plates and serve.