Preheat the oven to 300°F and line a baking sheet with parchment paper.
In a medium mixing bowl, combine the chia seeds, flax seeds, hemp seeds, pumpkin seeds, sunflower seeds, sesame seeds, and salt (if using). Stir well to evenly distribute all ingredients.
Drizzle the olive oil over the seed mixture and stir thoroughly until all seeds are lightly coated.
Spread the seed mixture in an even layer on the prepared baking sheet. Ensure the layer is no more than 1/4 inch thick for even roasting.
Bake in the preheated oven for 15 minutes, then stir the seeds gently with a spatula to promote even browning.
Return the baking sheet to the oven and bake for an additional 10-15 minutes, or until the seeds are golden brown and fragrant. Be careful not to overbake.
Remove the baking sheet from the oven and let the seeds cool completely on the sheet. They will crisp up as they cool.
Once cooled, transfer the seed mixture to an airtight container for storage.