13-ouncepackage strawberry gelatin (not sugar-free or fat-free)
¼cup butter, softened and diced
¾cupvegetable oil
½cupbuttermilk, room temperature
4large eggs, room temperature
1teaspoonvanilla extract
Frosting:
1cupbutter, softened
3 ¾cupspowdered sugar
3tablespoonsmilk, room temperature
Pinchsalt
½cupsliced strawberries, drained
Instructions
Cake
Preheat oven to 350 degrees F.
Add 1/4 cup sugar to sliced strawberries and allow to macerate for about half an hour or longer.
Mix cake mix, jello, and flour. Add butter pieces and mix until blended. Pour in oil. Add buttermilk and mix until well combined. Add eggs, one at a time, beating after each addition. Add vanilla extract and mix. Stir in strawberries and any accumulated juice.
Bake in shallow 9x13 dish for about 30 minutes.
Frosting
Beat softened butter until light and creamy. Gradually add powdered sugar. Add milk. Gently stir in strawberries until well-mixed.