Heat oven to 375°F. Line a medium or large rimmed baking sheet with parchment (or a silicone mat) and grease it generously. Melt the 2 tablespoons butter and transfer to a medium bowl. Add the sugar and stir with a soft spatula until coated.
Add the vanilla and salt and continue stirring until combined. Fold in the quinoa with a soft spatula, making sure it’s evenly coated in the sugar mixture and all the clumps are broken up. Spread the batter into the prepared pan, working to make it as thin and even as possible; 1/4-inch thick is ideal. (If you use a large pan, the batter won’t go all the way to the edges.)
Bake until the sugar melts, bubbles, spreads, and darkens. It should smell deeply toasted but not burned and look dry, not molten. Total time will be about 45 minutes, less for Florentine-style chewiness or longer for a brittle-like crunch. The darker the crackle is in the oven, the crisper it will be when you break it up. Transfer the pan to a wire rack to cool completely, at least 20 minutes.
To make the crackle, break the cooled quinoa sheet into bite-size pieces (If there are thicker parts you want more crisp, leave them behind on the parchment and pop the pan back into the oven, checking every 3 minutes.) Serve the crackle over fruit and whipped cream or yogurt, on ice cream or simple cake, or as a sweet, nutty garnish for salads or rice bowls. (Refrigerated in an airtight container, it actually gets crunchier and keeps for a week.)
— Recipe developed by The Bittman Project for Bob’s Red Mill