Preheat oven to 350F (175C). Grease and flour a 9x13 inch baking pan.
In a large bowl, whisk together flour, sugar, baking powder, and salt.
Add softened butter and milk to the dry ingredients. Mix on low speed until just combined.
Add eggs and vanilla extract. Beat on medium speed for 2 minutes until smooth and creamy.
Gently fold in freeze-dried strawberry powder until evenly distributed.
Pour batter into the prepared pan and spread evenly.
Bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.
Let cool in the pan for 10 minutes before inverting onto a wire rack to cool completely.
To make the frosting, beat softened butter in a large bowl until smooth and creamy.
Gradually add powdered sugar, beating until light and fluffy.
Add milk and strawberry powder. Beat until well combined.
Frost the cooled cake and decorate as desired.
For a more intense strawberry flavor, increase the amount of freeze-dried strawberry powder. Cake flour can be substituted for all-purpose flour for a more tender crumb. For vegan option, substitute plant-based butter, milk, and egg replacements.