Cinnamon Biscuits

1/8 cup plus 2 tablespoons sugar
2 cups all-purpose flour
2 cups cake flour
4 teaspoons baking powder
3/4 teaspoon salt
1/2 teaspoon ground cinnamon
1/4 teaspoon baking soda
3/4 cup (1 1/2 sticks) chilled unsalted butter, cut into 1/2-inch pieces
2 large eggs
1 cup chilled plain yogurt

Blend 2/3 cup sugar, flour, cake flour, baking powder, salt, cinnamon and baking soda in large bowl. Add butter, rub in with fingertips until mixture resembles coarse meal. Beat eggs in medium bowl. Transfer 1 tablespoon beaten eggs to small bowl; reserve for glaze. Whisk yogurt into remaining eggs in medium bowl. Stir yogurt mixture into dry ingredients. Gather dough into ball.
Gently knead dough on lightly floured surface until dough just holds together, about 6 turns. Roll or pat dough into 1-inch-thick round. Using 2 1/2- to 3-inch-diameter heart-shaped cookie cutter, cut out biscuits. Gather dough scraps, reroll to 1-inch thickness and cut out additional biscuits. Place biscuits on ungreased baking sheet. (Can be prepared 1 day ahead. Cover biscuits and reserved egg glaze separately and refrigerate.)
Preheat oven to 400°F. Brush biscuits with reserved egg glaze. Sprinkle with remaining 2 tablespoons sugar. Bake biscuits until puffed and light golden, about 18 minutes. Cool 10 minutes. Serve warm or at room temperature.