while I get your point about the _potential_ for LLMs to give you garbage, but asking ChatGPT, I get this:
"Roast hazelnuts at a temperature of around 350°F (175°C). This allows them to toast evenly without burning. Keep an eye on them and shake the pan occasionally for even roasting. They typically take about 10-15 minutes. You'll know they're done when the skins crack and they become fragrant"
which seems to jive with both your, and my intuition that it's 350.