For the cookies:
1 1/2 teaspoons blood orange zest
3/4 cup cocoa
2 1/2 cups powdered sugar
1/8 teaspoon salt
4 large egg whites
2 teaspoons vanilla
1 cup walnuts, coarsely chopped
For the parfaits:
6 cups nonfat Greek yogurt
1 1/2 cups powdered sugar
2 teaspoons vanilla
2 blood oranges
Mint sprigs, for garnish
Line a sheet pan with parchment paper. Heat oven to 350 degrees F. Zest one orange into a small bowl, reserve. In a large bowl or stand mixer, whisk cocoa, sugar and salt. In a glass measuring cup, combine egg whites and vanilla, then slowly beat into dry ingredients on low speed. Beat at medium speed for 2 minutes, until glossy. Mix walnuts and zest into batter. Drop scant quarter-cup mounds 3 inches apart on the prepared pan, and use a spoon to spread the batter out to half-inch thick cookies.
Put sheet pan on the middle oven rack and reduce heat to 325 degrees F. Bake cookies until thin cracks appear, about 15 to 17 minutes. Allow to cool completely before removing from the pan, peeling off the parchment paper if necessary.
Place yogurt in a medium bowl and stir in powdered sugar and vanilla; reserve. Cut an orange in half and squeeze juice from one half into a small cup. Use a knife to slice the rind and pith away from the remaining orange and half-orange, and then use a paring knife to remove segments from the white membranes. Cut segments in half crosswise.
To assemble, use eight wine glasses or glass ramekins. Break each cookie into 4 pieces. Place one-third cup of yogurt mixture in each glass or ramekin, then add 2 pieces of cookie. Top with another one-third cup yogurt, add 4 orange pieces and 2 more cookie pieces, then drizzle blood orange juice around the edge of glass. Repeat process.
Refrigerate for at least 2 hours, and garnish with sprigs of mint before serving.
It’s simple to cut this recipe in half when entertaining a smaller crowd, or to double the cookie recipe to have extras for snacking later! If you're not a fan of walnuts or absolutely love chocolate, you can substitute chocolate chips for all or half the walnuts in the cookies.