01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper to prevent sticking and ensure easy cleanup.
02 - In a medium bowl, whisk together the flour, sugar, baking powder, and salt until thoroughly combined.
03 - Add the cold cubed butter to the flour mixture. Using a pastry cutter or your fingertips, work the butter into the dry ingredients until the mixture resembles coarse crumbs with pea-sized butter pieces remaining.
04 - Pour in the milk and vanilla extract. Stir gently with a spatula or wooden spoon just until the dough comes together. Take care not to overmix, as this will result in tough shortcakes.
05 - Drop tablespoon-sized mounds of dough onto the prepared baking sheet, spacing them evenly. Bake for 12–15 minutes or until the tops are golden brown. Transfer to a wire rack and let cool completely.
06 - While the shortcakes bake, combine the sliced strawberries, sugar, and lemon juice in a bowl. Toss gently to coat and let sit for at least 15 minutes, allowing the berries to release their juices and create a syrupy macerate.
07 - In a chilled bowl, beat the cold heavy cream, powdered sugar, and vanilla extract with an electric mixer on medium-high speed. Continue beating until soft, billowy peaks form when the beaters are lifted.
08 - Crumble the cooled shortcake biscuits into bite-sized chunks. In four parfait or dessert glasses, create layers by adding shortcake crumbles, followed by a spoonful of macerated strawberries, then a dollop of whipped cream. Repeat the layering process, finishing with whipped cream on top. Garnish each glass with a decorative strawberry slice.
09 - Serve the parfaits immediately for optimal texture, or refrigerate for up to 2 hours before serving. If chilling, add the final garnish just before serving to maintain freshness.