3-Ingredient Strawberry Tart with Lemon Whipped Cream

For Strawberry Tart: 1 (12x12-inch) sheet puff pastry, thawed 16 oz. fresh strawberries, sliced 1 Tablespoon sugar or sugar substitute For Lemon Whipped Cream: 1 cup chilled heavy cream 2 Tablespoons powdered sugar Zest and juice from 1/2 lemon