Fluffy Yellow Layer Cake Recipe (Cooks Illustrated)

Fluffy Yellow Layer Cake (Cooks Illustrated)

Ingredients:
Cake flour, 2 ½ cups (10 oz, plus extra for dusting pans)
Baking Powder, 1 ¼ tsp
Baking Soda, ¼ tsp
Table salt, ¾ tsp
Sugar, 1 ¾ cups (12 ¼ oz)
Unsalted butter (melted and cooled slightly) 10 tbsp, (1 ¼ sticks) 
Buttermilk (room temperature), 1 cup
Vegetable oil, 3 tbsp
Vanilla Extract, tsp
Large egg yolks (room temperature), 6 ea (plus large egg whites, 3 ea) 

Directions:

1. Adjust the oven rack to the middle position of the oven and heat the oven to 350 degrees F (we recommend 325 degrees F). Grease and flour two 8” x 2” round pans, PRD-82. You can line the bottom with a parchment circle, if desired.
2. Whisk flour, baking powder, baking soda, salt and 1 ½ cups of sugar together in a large bowl. In a 4-cup liquid measuring cup or medium bowl, whisk together melted butter, buttermilk, oil, vanilla and yolks.
3. In a clean stand mixer bowl fitted with a whisk attachment, beat egg whites at medium-high speed until foamy, about 30 seconds.  With machine running, gradually add remaining ¼ cup of sugar, continue to beat until stiff peaks just form. 30-60 seconds (whites should hold peak but moisture should appear moist). Transfer to bowl and set aside.
4. Add flour mixture to now empty mixing bowl, fitted with whisk attachment. With mixer running on low speed, gradually pour in butter mixture and mix until almost incorporated (a few streaks of dry flour with remain), about 15 seconds. Stop mixer and scrape whisk and sides of the bowl. Return mixer to medium-low speed and beat until smooth and fully incorporated, 10-15 seconds.
5. Using rubber spatula, stir 1/3 of whites into batter to lighten, then add remaining whites and gently fold into batter until no white streaks remain. Divide batter evenly between prepared cake pans. Lightly tap pans against counter 2 or 3 times to dislodge and large air bubbles. 
6. Bake until cake layers begin to pull away from sides of pan and toothpick inserted into center comes out clean, 25-30 minutes. Cool cakes in pans on wire cooling racks for 10 mins. Loosen cakes from sides, then invert onto a wired cooling rack. Peel off parchment paper. Invert cakes again and allow to cool completely.