Celeriac, sage & chicken risotto

Name: Celeriac, sage & chicken risotto
Cuisine: European, Italian, Mediterranean
Ingredients: 20g salted butter; 3 tbsp extra virgin olive oil; 1 onion, finely chopped; 2 cloves garlic, thinly sliced; 500g celeriac, peeled and cut into 2cm pieces; 1 litre fresh chicken stock; 300g Arborio rice; 250ml white wine; 1 tsp salt; 2 large chicken breasts, cut into strips SAGE BUTTER; 50g salted butter; 10 sage leaves, finely chopped