For the cupcakes:
1½ cups all-purpose flour
1½ cups cake flour, sifted
1 tbsp. baking powder
1 tsp. salt
1 tbsp. ground cinnamon
2 sticks (1 cup) unsalted butter, at room temperature
1¾ cups sugar
4 large eggs
2 tsp. vanilla extract
1¼ cups milk
For the frosting:
¾ cup plus 1 tbsp. sugar, divided
1/3 cup water
1 tbsp. light corn syrup
3 large egg whites, at room temperature
1 tsp. ground cinnamon
2 tbsp. sugar
To make the cupcakes, preheat the oven to 350° F. Line cupcake pans with paper liners. Combine the flours, baking powder, salt and cinnamon in a medium bowl; whisk to combine. In the bowl of an electric mixer, beat the butter and sugar on medium-high speed until light and fluffy, about 3 minutes. Beat in the eggs one at a time, mixing well after each addition. Blend in the vanilla. With the mixer on low speed, add in the dry ingredients in three additions alternating with the milk, beginning and ending with the dry ingredients. Beat each addition just until incorporated.
Divide the batter evenly between the prepared cupcake liners, filling each three-quarters full. Bake, rotating the pans halfway through, until a toothpick inserted in the center comes out clean, about 18-20 minutes. Allow to cool in the pans about 5 minutes before transferring to a wire rack to cool completely.
To make the frosting, combine the sugar, water and corn syrup in a saucepan with a candy thermometer clipped to the side. Bring to a boil over medium heat, stirring occasionally so the sugar dissolves. Continue boiling without stirring until the temperature reaches 230° F.
In the meantime, while the sugar mixture is heating, beat the egg whites in the bowl of an electric mixer fitted with the whisk attachment. Whisk on medium-high speed until medium-soft peaks form. As soon as the sugar mixture reaches 230° F, remove the pan from the heat. With the mixer on medium-low, pour the syrup down the side of the bowl in a slow steady stream until it has all been added to the bowl. Increase the mixer speed to medium-high and whisk until the bottom of the bowl is completely cool to the touch and stiff peaks form, about 7 minutes. Use immediately.
Frost the cooled cupcakes as desired. (I used an Ateco tip #829 to frost these cupcakes.) In a small bowl, whisk together the ground cinnamon and sugar. Sprinkle a pinch of the cinnamon-sugar on top of each frosted cupcake. Garnish with mini snickerdoodles.
*To make the mini snickerdoodles, I used a half recipe of regular snickerdoodles (and didn’t even use all of the dough) and rolled the dough into tiny balls, about ¾-inch diameter. I reduced the baking time to about 8-10 minutes.