Prep the strawberries. Rinse, hull, and slice the strawberries. If they’re not very sweet, toss them with a tiny pinch of sweetener and let them sit for 5 minutes to release their juices.
Whip the cream. In a cold mixing bowl, beat the heavy cream with a hand mixer until soft peaks form.
Don’t overbeat—soft and billowy is perfect.
Blend the mascarpone. In a separate bowl, add mascarpone, powdered sweetener, vanilla, lemon zest (if using), and a pinch of salt. Beat on low until smooth and creamy, about 30–45 seconds.
Fold together. Gently fold the whipped cream into the mascarpone mixture in two additions. Use a spatula and light strokes to keep it airy.
Assemble the dessert. Spoon a layer of mascarpone mousse into small glasses or bowls, add a layer of strawberries, then repeat.
Aim for 2 layers of each for a pretty, parfait-style look.
Chill (optional but recommended). Refrigerate for 20–30 minutes to set and let the flavors meld. This makes the texture extra silky.
Finish and serve. Top with a few more strawberry slices, a sprinkle of chopped nuts, or a mint leaf. Serve cold.