Trail Mix Muffins

1/4 c. quinoa
2/3 c. whole wheat pastry flour
2/3 c. all-purpose flour
2 tsp. baking powder
1/2 tsp. cinnamon
1/4 tsp. salt
1/2 c. packed dark brown sugar
1/4 c. plus 2 Tbsp. crunchy peanut butter
1/4 c. unsalted butter cut into small chunks, plus more for greasing
1 large egg yolk, at room temperature
1 1/2 tsp. vanilla extract
2/3 c. low-fat milk
1/3 c. dried cranberries
1/3 c. semisweet chocolate chips
2 large egg whites, at room temperature

Fill a medium saucepan with water and bring it to a boil over high heat.  Add the quinoa and reduce the heat to low.  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 cold water.

Position rack in the center of the oven and heat to 400 F.  Use a crumpled sheet of waxed paper to lightly butter the wells of a muffin tin.

In a medium bowl, whisk together both flours, the baking powder, cinnamon, and salt until well blended.

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 creamy and smooth - 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 gradually beat in the milk.

With a rubber spatula, fold the flour mixture into the wet ingredients.  Next, fold in cranberries and chocolate chips until they're evenly distributed in the batter.

In a large bowl with a mixer set at high speed and beaters that have been cleaned and dried, beat the egg whites until soft peaks form, about 1 minute.  Use a rubber spatula to gently fold the egg whites into the batter.

With a large spoon or ice cream scoop, fill each well of the muffin tin 3/4 full with batter.

Bake the muffins until they're brown and firm, about 20 minutes, turning the pan halfway through.  Coll them in the pan for 5 minutes and then transfer them to a rack to cool completely.