Step 1Preheat the oven to 190 °C/ 375 °F (fan assisted), or 210 °C/ 410 °F (conventional). Spread the hazelnuts, macadamia nuts, and almonds on a baking tray and transfer to the oven. Bake for about 8-10 minutes, until lightly browned. Remove the nuts from the oven and let them cool for 15 minutes. (You can skip the roasting if you are using peeled roasted hazelnuts.)
Note: If using whole unpeeled hazelnuts: Once roasted and cooled, rub the hazelnuts together in your hands to remove the skins. This makes the butter smooth and avoids the bitter taste imparted by the skins.