Soft, moist vanilla sheet cake topped with strawberry buttercream - you'll love the flavor combo and pretty pink color of this vanilla cake with fresh strawberry frosting.
Grease and flour a 9x13 inch baking pan. Or line the bottom with parchment paper, and grease the sides.
In a medium-sized bowl whisk together the flour, baking powder, baking soda and salt. Then set aside.
2 ½ Cups Cake Flour, 1 ½ teaspoons Baking Powder, 1/2 teaspoon Baking Soda, 1/4 teaspoon Salt
Then in a second large bowl using a hand-held mixer on medium speed, beat the butter and sugar together until fluffy (about 2 minutes).
3/4 Cup Unsalted Butter, 1 ½ Cups Granulated Sugar
Add in the 2 large eggs, 2 egg whites and vanilla extract and continue beating until combined (about 30-60 more seconds).
2 Large Eggs, 2 Egg Whites, 2 teaspoons Vanilla Extract
Turn off the mixer and scrape down the sides of the bowl as needed.
Then beat in the sour cream, followed by about 1/2 of the flour mixture.
1/4 Cup Sour Cream
Finally, beat in the milk followed by the remaining flour mixture. Be careful not to over mix.
3/4 Cup Milk
Pour the batter into the prepared pan and bake for 30-35 minutes or until an inserted toothpick comes out clean.
Allow the cake to cool fully before frosting.
Strawberry Buttercream Frosting
Core the strawberries to remove the white centers, then pulse in a food processor or blender until smooth.
1 ½ Cups Fresh Strawberries
Then put the strawberry puree through a sieve to remove the seeds. You'll likely need to press the mixture through using a spatula or spoon. You should end up with about 1 and 1/2 to 1 and 1/4 cups of strawberry puree
Pour the strawberry puree into a medium-sized saucepan over low-medium heat.
Heat the puree until it gently boils while stirring occasionally.
Allow the mixture to boil gently for 10-15 minutes until it's thick in consistency and dark red-ish pink in color.
When the mixture is done boiling, You should have about 1/3 cup left. Put the reduced strawberry puree in the fridge or freezer to cool fully.
To make the frosting, in a large bowl using an electric mixer on medium speed, beat the butter until fluffy.
1 Cup Unsalted Butter
Then turn the mixer down to low speed and beat in 2 cups of the powdered sugar.
4-5 Cups Powdered Sugar
Then turn off the mixer and add in 1/4 cup of the reduced strawberry puree (it must be cold when added), the vanilla and salt.
1/4 teaspoon Vanilla Extract, 1/4 teaspoon Salt
Beat together on low speed.
Then beat in an additional 2 cups of powdered sugar.
4-5 Cups Powdered Sugar
Once combined, turn the mixer up to medium speed and beat for an additional 30 seconds.
Beat in a little extra powdered sugar, and up to 1 tablespoon of cream as needed to get the desired consistency and sweetness level.
1 Tablespoon Whipping Cream
Frost the cooled cake with the strawberry frosting, and optionally decorate each piece with half a strawberry.
Notes
**Leftovers can be stored in the fridge in an air-tight container for up to 3 days.