1. Gather all your ingredients and tools, including a mixing bowl, hand mixer, spatula, and serving jars or cups.
2. Allow the cream cheese to soften at room temperature for easier blending and a smooth consistency.
3. Combine the softened cream cheese, sugar, vanilla extract, and lemon juice in a large mixing bowl. Mix thoroughly using a hand mixer until smooth and lump-free.
4. Gradually add heavy cream to the cream cheese mixture while continuing to blend. Beat until the mixture becomes fluffy and forms soft peaks.
5. For the blackberry sauce, combine fresh or frozen blackberries with sugar and lemon juice in a saucepan. Simmer over low heat until the berries release their juices, stirring occasionally.
6. Strain the blackberry sauce to remove seeds for a smooth texture. Allow the sauce to cool before assembling the parfaits.
7. Prepare your base layer by adding graham cracker crumbs or your chosen nuts to the bottom of each jar or serving glass. Compress gently to create a sturdy base.
8. Spoon a generous layer of the cheesecake mixture on top of the base.
9. Add a spoonful of the blackberry sauce to create a contrasting layer. Swirl lightly if desired.
10. Repeat the layers, alternating between the cheesecake mixture and blackberry sauce, until the jar or glass is filled to your preferred height.
11. Optional: Finish the parfait with a dollop of whipped cream and garnish with a fresh blackberry or mint leaf for decoration.
12. Refrigerate the assembled parfaits for several hours to allow the layers to set and flavors to meld.
13. Serve chilled and enjoy your delightful, no-bake Blackberry Cheesecake Parfaits.