Prep the berries: Rinse and pat dry.
Slice strawberries if using. Toss with a small squeeze of lemon juice and a light sprinkle of sweetener if your berries aren’t very sweet. Add a pinch of lemon zest and, if you like, a half teaspoon of chia to thicken any juices.
Make the cream layer: In a bowl, beat heavy cream to soft peaks.
In a separate bowl, stir together Greek yogurt, mascarpone (or cream cheese), vanilla, a pinch of salt, and sweetener to taste. Gently fold the whipped cream into the yogurt mixture until smooth and fluffy.
Taste and adjust: Add more sweetener or a touch more vanilla if needed. The mixture should be lightly sweet with a creamy, tangy finish.
Layer the parfaits: Spoon a layer of cream into glasses or jars.
Add a layer of berries. Repeat until you reach the top, finishing with berries.
Add crunch: Sprinkle with chopped nuts, coconut flakes, or a small handful of low-carb granola right before serving so it stays crisp.
Chill (optional): For a firmer set and deeper flavor, chill for 30–60 minutes before serving.