1. Fill a medium saucepan with water and bring it to a boil over high heat. Add the quinoa, reduce the heat to low, and simmer until the grains have popped open and appear translucent, about 12 minutes. Drain the grains in a fine mesh sieve and rinse them with cool water.
2. Position the rack in the center of the oven and heat to 400 degrees . Use a crumpled sheet of waxed paper to lightly butter the wells of a muffin tin.
3. In a medium bowl, whisk together both flours, and the baking powder, cinnamon, and salt until well blended.
4. In a large bowl, with a hand mixer set at medium speed, beat together the brown sugar, peanut butter, and butter, scraping down the sides as needed, until smooth and creamy, about 5 minutes. Beat in the egg yolk and vanilla until smooth, then beat in the quinoa, continuing to scrape down the sides as you work. Reduce the mixer’s speed to low and…