You must use block cream cheese. You can substitute ⅓ less fat block cream cheese if you prefer.
If you want to use homemade whipped cream, follow these instructions: In a cold metal bowl of a stand mixer or in a large cold metal mixing bowl with a hand mixer, use cold beaters to beat 1½ cups cold heavy whipping cream, ¾ cup powdered sugar and 1 teaspoon vanilla extract until stiff peaks form. Also feel free to substitute Lite Cool Whip.