Center a rack in the oven and preheat to 325 (F). Prepare a baking sheet by lining with parchment paper and set aside.
Heat a medium, heavy-bottomed skillet over medium heat until very hot. Add 2 teaspoons of the amaranth seeds and shuffle the pan so that they are in a single layer; the seeds will begin popping immediately. Shake the pan frequently, every few seconds, keeping the amaranth in a single layer until about half the seeds have popped (they will turn white in color when they do) and the rest are golden. Tip these into a large bowl, and repeat until all the amaranth has been popped or toasted.
To the bowl of popped amaranth, add 2 1/2 cups old-fashioned rolled oats, 1 cup whole raw almonds, 1/4 cup dark brown sugar, 1/4 cup plus 2 tablespoons maple syrup, 1/4 cup plus 2 tablespoons olive oil, 3/4 teaspoon kosher salt, 1 teaspoon pure vanilla extract, and fresh zest from 1 large orange. Stir very well to combine, making sure to evenly distribute the salt and amaranth seeds.
Scrape the mixture onto the lined baking sheet, and use a rubber spatula to spread it to a thin layer across the pan. Ideally, the edges will be slightly thicker than the center, as they weill bake faster. Lay a second piece of parchment over the granola, and place the second sheet pan on top, right side up, making a little granola sandwich.
Transfer to the preheated oven and bake for 20 minutes. Rotate and continue baking for another 10 to 20 minutes for a total of 30 to 40 minutes or until the granola is a rich golden brown, peeking under the parchment to make sure that the edges aren't burning. When you pull it out of the oven, it will still be soft, but will crisp as it cools.
Let the granola cool completely in the sheet pan sandwich on a wire rack, about 1 to 2 hours, before breaking up into large sheets or clumps and storing in an airtight container for up to 1 month.