Preheat oven to 350°F. Line a 9x13-inch pan with foil or parchment paper and spray with nonstick cooking spray.

Add cake mix, butter and eggs to a large bowl. Stir until combined. You can do this by hand or use a mixer.

Press batter evenly into prepared pan. Bake until light golden around the edges and no longer glossy, approximately 15-20 minutes. Cool completely before frosting.

To make the frosting, beat cream cheese with powdered sugar and vanilla until smooth. Mix on high speed while adding heavy whipping cream, then mix until stiff peaks form.

Frost bars as desired. Store leftover frosting in the refrigerator for up to 3 days.

Just before serving, top bars with sliced strawberries. Slice and serve.

Store bars in refrigerator for up to 24 hours once berries are added. Make bars up to 2 days in advance and frosting up to 2 days ahead. Don’t assemble until ready to serve.