Clean and remove the stems on about 1 1/2 quarts of strawberries. Cut them in half and place them in a food processor to blend them into a puree. You should end up with about 3 cups of strawberry purée .
Place the strawberry purée in a small saucepan. Cook over medium-low heat, stirring often to prevent burning, until the strawberries have reduced to 1 1/2 cups of puree. I've found this to take about 30-45 minutes.
Allow the reduced strawberry purée to cool completely. (I often make this a day in advance so it has plenty of time to cool.)
For the Cupcakes:
Preheat the oven to 350 degrees Fahrenheit.
Sift together the cake flour, baking powder, soda and salt into a medium size bowl. Set aside.
In the bowl of stand mixer, cream together the softened butter and sugar.
Add the milk, oil and extracts. Beat on medium speed for 2 minutes.
Add the reduced strawberry purée and egg whites. Beat for an additional 2 minutes.
Add the flour mixture and stir until well combined, but be careful not to overmix. Scrape the sides of the bowl as needed.
Place cupcake liners in 20 muffin cups. Divide the batter between the 20 cups.
Bake for 18-20 minutes, or until the cupcakes spring back when you touch the center of it. Allow the cupcakes to cool completely on a wire rack.
For the Buttercream:
In a stand mixer bowl, with the mixer on medium speed, whip the butter for 2-3 minutes until it is almost white in color.
Add in the salt, powdered sugar, vanilla extract. Mix on low speed until blended.
Add in the reduced strawberry purée , 1/4 a cup until the frosting is the consistency you'd like.
Add a drop or two of red food coloring if you'd like the cake to be a little pinker. Beat on low speed again for 1-2 minutes.
Assemble the Cupcakes:
Cut the tip of a disposable frosting bag. Place a large Wilton tip (1A, 1M or 2D) inside the bag. Fill the frosting bag with the strawberry buttercream.
Pipe the cupcakes by swirling the frosting onto the cupcake.
Store the cupcakes in an airtight container in the refrigerator for 3-4 days. You can also freeze the cupcakes for up to 2 months.
This makes a lot of frosting so that you can swirl it a couple inches high on the cupcakes. If you just want a thin layer of frosting, make half a recipe.The calories shown are based on the recipe making 20 cupcakes, with 1 serving being 1 cupcake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information. The information in the nutrition box are calculated through a program and there is room for error. If you need an accurate count, I recommend running the ingredients through your favorite nutrition calculator.**