Preheat the oven to 350℉. Grease and line a 9x13-inch cake pan with parchment paper. Set aside. In the bowl of the stand mixer, fitted with the paddle attachment, sift together the flour, sugar, milk powder, baking powder, baking soda, and salt.
3 (375 g) cups Cake Flour , 2 (400 g) cups Granulated Sugar , 2 tablespoons Milk Powder , 2 ½ teaspoons Baking Powder, ½ teaspoon Baking Soda , ¾ teaspoon Kosher Salt
With the mixer on low speed, slowly add in the butter, one slice at a time to the flour mixture. Mix until the butter is incorporated and starting to break into smaller clumps, about 2 minutes. Once all the butter is added, keep the mixer on low speed and slowly add in the oil. Continue to mix for 1 minute. Once combined, the mixture will look very crumbly in texture, like wet sand. ½ (113 g) cup Unsalted Butter , ½ (112 g) cup Vegetable Oil
In a large mixing cup, whisk together the sour cream, milk, and vanilla extract. With the mixer on low speed, pour the milk mixture into batter and mix for 30 seconds. Then, increase the speed to medium and mix for an additional 30 seconds. After mixing, scrape the bottom and sides of the bowl with a rubber spatula. Dry ingredients like to stick to the bottom so be sure to scrape the bowl well!!
½ (120 g) cup Sour Cream , 1 (240 g) cup Whole Milk , 1 tablespoon Vanilla Extract
Whisk together the eggs and slowly add half of the egg mixture to the batter on low speed. Once the egg mixture has incorporated into the batter, stop the mixer and scrape down the bowl. With the mixer on low, slowly add the second half of the egg mixture. After all of the egg mixture is incorporated, scrape the bowl and mix the batter on low for 10 seconds. Increase the speed to medium and continue to mix the batter for an additional 10 seconds, being careful not to over mix.
4 large Eggs
Remove the bowl from the stand mixer and scrape the bottom and sides of the bowl with a rubber spatula to ensure everything is combined. The batter should be thick and creamy. Pour the batter into the prepared cake pan and bake for 35 to 40 minutes. When done, the cake should be golden brown in color and bounce back when lightly pressed. The edges of the cake should slightly pull away from the sides of the pan. A cake tester inserted into the center should come out clean or with a few moist crumbs.
Allow the cake to cool in the pan for 10 minutes, then using the parchment overhang, gently lift the cake out of the pan and onto a wire rack. Allow the cake to cool for 30 minutes before flipping it over to remove the parchment paper. (I like to do this by placing another wire rack on top of the cake, flip it so the parchment paper is now on top then remove the paper. Then repeat the process by placing the wire rack on top of the cake again and flipping it back over so its right side up.)Let the cake cool completely, about two hours before making the frosting. If you didn't make it ahead, as the cake cools, make the strawberry filling.