Ingredients
2¼cupsall-purpose flour,heat-treated, spoon and leveled
2¼tspcornstarch
¾tspsalt
¾cupunsalted butter,softened to room temperature
1cuplight brown sugar,or dark, packed
⅓cuppasteurized egg whites,at room temperature
2tsppure vanilla extract
1cupmini semi-sweet chocolate chips
1¾cupsall-purpose flour,spoon and leveled
1tspbaking powder
¼tspBaking Soda
½tspsalt
½cupwhole milk,at room temperature
½cupsour cream,at room temperature
½cupunsalted butter,(1 stick), softened to room temperature
1cupgranulated sugar
⅓cuppasteurized egg whites,at room temperature
2tsppure vanilla extract
1cupunsalted butter,(2 sticks), softened to room temperature
2tsppure vanilla extract
1tbspheavy cream or milk
1tspsalt
3cupsconfectioners’ sugar,sifted
remaining cookie dough
Preparation
In a medium bowl, whisk the heat-treated flour, cornstarch, and salt together. Set aside.
Using a handheld or stand mixer fitted with the paddle attachment, beat the butter on medium speed in a large bowl for about 2 minutes until smooth and creamy. Add the brown sugar and mix on medium for about 3 full minutes until light and fluffy.
Using a rubber spatula, scrape down the sides and up the bottom of the bowl as needed. Add the egg whites and vanilla extract and mix for about 2 minutes until fully incorporated.
Add half of the flour mixture and mix on Low for about 15 seconds or just until the powdery texture of the flour disappears. Immediately add the rest of the flour mixture and mix until combined. Remove the bowl from the mixer and use a rubber spatula to fold in the chocolate chips.
Freeze or refrigerate the cookie dough for about 15 minutes or until the dough is easy to handle. Roll the dough into 12 one-tablespoon-sized balls, place on a plate lined with parchment paper, then refrigerate. Cover the remaining cookie dough and set aside at room temperature.
Preheat the oven to 350 degrees F. Line a 12-cup muffin pan with cupcake liners.
Whisk the flour, baking powder, baking soda, and salt together in a medium bowl. In a small bowl, whisk the milk and sour cream together until smooth. Set aside.
Using a handheld or stand mixer fitted with the paddle attachment, beat the butter and sugar together on medium speed in a large bowl for about 3 minutes until light and fluffy. Using a rubber spatula, scrape down the sides and up the bottom of the bowl as needed.
Add the egg whites and vanilla and beat for about 2 minutes, or until the mixture is totally incorporated. With the mixer on Low, alternate additions of the flour mixture and the sour cream mixture, starting and ending with flour. Beat for about 30 seconds or until the batter appears smooth and creamy.
Fill cupcake liners about ¾ full. Bake for about 16 to 19 minutes or until the cupcake edges are golden brown and a toothpick inserted in the center comes out clean. Remove from the oven and let cool in the pan for about 5 minutes.
Remove cupcakes from the pan and carefully press 1 chilled cookie dough ball into the center of each cupcake. The dough ball might not sit completely flat, so expect a little lump on top — which will be covered with frosting later on. Cool cupcakes completely.
Using a handheld or stand mixer fitted with the paddle attachment, beat the butter in a large bowl on medium speed for about 3 minutes, or until light, fluffy, and completely smooth. Add the vanilla extract, milk, and salt and beat until combined. Using a rubber spatula, scrape down the sides and up the bottom of the bowl as needed.
Add the confectioners’ sugar, then beat on low speed for about 15 seconds. Switch to medium-high speed and beat the frosting for about 4 to 5 minutes until super light and fluffy. The frosting will become lighter in color as air is whipped into it.
Break the remaining cookie dough into quarter-sized chunks. (If desired, save enough dough to make 12 little cookie dough balls as a garnish on top!) With the mixer running on medium speed, add the cookie dough chunks. Mix just until incorporated – some chunks can remain.
Once the cupcakes are completely cool, top with frosting (or spread the frosting with a knife or icing spatula, or apply with a large round piping tip.)
Decorate with chocolate chips, sprinkles, or any leftover cookie dough, if desired. Leftover cupcakes keep well covered tightly in the refrigerator for 3 days.
