Place the cottage cheese in a food processor or blender and blend until completely smooth, about 1 to 2 minutes. Scrape down the sides as needed.
Add the strawberries, granulated sugar, vanilla extract, and lemon juice to the blender. Blend again until the mixture is silky and well combined.
In a separate mixing bowl, whip the cold heavy whipping cream with the powdered sugar using a hand mixer or stand mixer until soft peaks form, about 3 to 4 minutes.
Gently fold the whipped cream into the strawberry-cottage cheese mixture using a spatula. Take your time to keep the mousse light and airy.
Divide the mousse into serving dishes or glasses, smoothing the tops.
Chill in the refrigerator for at least 1 hour to set and develop flavor.
Optional: Garnish with fresh strawberry slices or a sprig of mint before serving.