Preheat your oven to 350F. Prepare a baking tray by lining it with a silicone baking mat.
Combine your oats, nuts, seeds, salt, and optional cinnamon in a large bowl. Scatter half the mixture onto the prepared baking tray (we will be toasting the muesli in two batches, so set the other half off to the side for now).
Place the baking tray in the preheated oven and bake for 10-12 minutes, or until everything is lightly toasted.
Remove from the oven, and carefully use a spatula or large spoon to give the oat mixture a mix. Sprinkle the dried coconut flakes on top and return to the oven. Bake until the coconut flakes are lightly toasted, this typically only takes about 1-2 minutes.
Remove from the oven and let cool for about 10 minutes, then transfer to another large bowl. Scatter the second half of the mixture onto the baking tray, repeat steps 3-4 with this second half, let cool, and add to the large bowl to combine both batches. (If your mixture is still pretty warm, wait a few minutes longer before moving onto step 6).
Add the dried cranberries and raisins to the bowl and toss everything to combine.
Serve your muesli however you wish! You can enjoy it cereal-style with a bit of cold nondairy milk, oatmeal-style by adding a bit of nondairy milk and then heating the mixture on the stovetop or the microwave, or parfait-style with a bit of nondairy yogurt. You may also want to add sweetener of your choice (such as maple syrup) before digging in, or throw on some additional toppings (such as fresh fruit).