Preheat the oven to 170°C (340°F). Spread the hazelnuts and almonds out on a baking sheet. Roast them for 20-30 minutes.
Add the sugar to a saucepan on medium heat to create a caramel. Let the sugar melt until it has a golden caramel color, but not too dark.
Add the, still warm, nuts to the pan with the caramel and mix to evenly coat the nuts.
The sugar will recrystallize. Keep the pan on the heat and let the sugar melt once more, stirring occasionally.
Once the caramel has remelted, dump the entire mixture out onto a sheet of parchment paper and let cool completely.
Once the caramel has cooled, break it up into smaller pieces and transfer to a food processor fitted with the blade.
Turn on the food processor and let it run until it turns into a liquid paste, scrapping down the sides occasionally. This can take anywhere from 5-15 minutes depending on your food processor.
Transfer to a container and store somewhere dark, like the back of your pantry, until needed.